visible absorption spectrophotometry: 2009–2011

Microchemical Journal 106 (2013) 1–16

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Review article

Recent applications in derivative ultraviolet/visible absorption spectrophotometry: 2009–2011 A review C. Bosch Ojeda, F. Sanchez Rojas ⁎ Department of Analytical Chemistry, Faculty of Sciences, University of Málaga, Campus Teatinos, 29071 Málaga, Spain

a r t i c l e

i n f o

Article history: Received 8 May 2012 Received in revised form 21 May 2012 Accepted 22 May 2012 Available online 26 May 2012 Keywords: Derivative UV–vis Multi-component analysis Pharmaceutical analysis Metal ion analysis Review

a b s t r a c t Derivative spectrophotometry (DS) has been introduced for the resolution of overlapping peaks. DS method has been widely used to enhance the signal and resolve the overlapped peak-signals due to its advantages in differentiating closely adjacent peaks, and identifying weak peaks obscured by sharp peaks. In this work, the analytical applications of derivative UV/VIS region absorption spectrophotometry produced in the last 3 years (since 2009) are reviewed. © 2012 Elsevier B.V. All rights reserved.

Contents 1. 2.

Introduction . . . . . . . . . . . . . . Theoretical and instrumental aspects . . . 2.1. Method of disturbing effect . . . . 2.2. Method of sixteen solutions . . . . 3. Applications . . . . . . . . . . . . . . 3.1. Inorganic analysis . . . . . . . . . 3.2. Pharmaceutical analysis . . . . . . 3.3. Stability-indicating methods . . . . 3.4. Analysis of biological compounds . 3.5. Food analysis . . . . . . . . . . . 3.6. Environmental analysis . . . . . . 3.7. Other analysis . . . . . . . . . . 4. The derivative technique as a tool for green 5. Conclusions . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . .

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1. Introduction Application of derivative technique of spectrophotometry offers a powerful tool for quantitative analysis of multi-component mixtures. When derivatised, the maxima and minima of the original function

⁎ Corresponding author. Tel.: + 34 952137393; fax: + 34 952132000. E-mail address: [email protected] (F. Sanchez Rojas). 0026-265X/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.microc.2012.05.012

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1 2 2 2 3 3 3 5 10 10 11 12 12 13 13

take zero values, and the inflections are converted into maxima or minima, respectively. The derivative curves are more structured than the original spectra, thus enabling very tiny differences between the original spectra to be identified. DS method has been widely used to enhance the signal and resolve the overlapped peak-signals due to its advantages in differentiating closely adjacent peaks, and identifying weak peaks obscured by sharp peaks. The main disadvantage of D is its dependence on instrumental parameters like speed of scan and the slit width. The instrumental

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C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

conditions of recording parent zero-order spectrum have strong influence on the shape and intensity of its derivative generations. In general, DS has been directly used for the simultaneous determination of organic and inorganic compounds. Fig. 1 shows the applications of DS in several areas since last three decades ago. As can be seen from this figure pharmaceutical and inorganic analyses are two areas where DS has been more used. DS offers greater selectivity than normal spectrophotometry in the simultaneous determination of two or more components without previous chemical separation. Principles, advantages and applications of this technique have been reviewed in four works published some years ago [1–4]. In these works, we exposed the different aspects of derivative ultraviolet/visible spectrophotometry: theoretical, instrumental devices and analytical applications, the first until 1986, the second until 1993, the third until 2003 and the fourth until 2008. The purpose of this paper is to review the articles on the anterior cited aspects published since 2009, in order to complete the review since our last publication [4]. The great interest of this technique can be demonstrated from the increasing number of paper that appeared in the literature since three decades ago, as can be seen in Fig. 2. 2. Theoretical and instrumental aspects The determination of the analytical wavelength (the wavelength at which the binary system is analyzed by DS) involves the analysis of the derivative spectra. At the points where one of the components of the mixture crosses the zero line, the value of the mixture derivative should, according to the principle of the derivative additivity, be equal to the derivative of the second component. However, this method, referred to as the zero-crossing technique, sometimes requires the analysis of the spectrum at many wavelengths. This refers particularly to the spectra with high course variation and high order derivative spectra. Currently, the determination of the measuring points is easier only in the ratio spectra derivative method, which does not make use of the zero crossing technique for the reading of the derivative value. In this way, Krystek [5] proposes two methods of preliminary selection of wavelengths which may meet the requirements for the analytical wavelengths, whose proposed names are: “the method of disturbing effect” and “the method of sixteen solutions.” They are presented using, as example, 2,4-dichlorophenoxyacetic acid (2,4D), 2-(4-Chloro-2-methylphenoxy)propionic acid (MCPP), and 2-(2,4Dichlorophenoxy)propionic acid (2,4DP), which have very similar but, at the same time, very complex spectra. 2.1. Method of disturbing effect Derivative spectra were recorded for a series of solutions where the concentration of one of the analyzed components is constant

1% 3% 6%

22%

12% 5% inorganic organic pharmaceutical

51%

biological food environmental other

Fig. 1. Application of DS in different areas.

Fig. 2. Evolution of DS publications from 1980 until today.

while the concentration of the other changes. The points at which all the curves intersect are the points which may meet the requirements for the analytical wavelengths. The more distant they are from the zero line, the more sensitive is the method at the given wavelength. The points which are close to the zero line indicate low sensitivity of the determination. The closer the intersection points of the curves, the more precise the determination at these wavelengths.

2.2. Method of sixteen solutions It involves preparation of a series of 16 solutions of two analyzed components. In the series, each of the four concentrations of one component corresponds with four different concentrations of the other. The intersection points of the four curves representing the same concentrations of one component and different concentrations of the other may represent the analytical wavelengths for the first component. The combined use of DS and chemometric techniques has demonstrated to be a highly convenient choice in the determination of multicomponent matrices presenting serious spectra overlapping, thanks to their common potential ability to exploit minor spectral features. In this sense, De Luca et al. [6] develop three multivariate procedures, based on PCR, PLS1 and PLS2 algorithms that have been applied on absorbance data of a ternary mixture of drugs. The main goal of the work was a detailed comparison between the regression methods when they are applied on ordinary or derivative spectral data. The influence of the derivative order from zero to four on the prediction ability of the methods was investigated by the authors. Design of experiments and calibration optimization was used as chemometric tools to assist the development of the analytical methods. In this work a suitable mixture design associated with response surface methodology was defined, able to build a calibration set covering an experimental domain which reflects the component combination in the real samples. Validation of the models was performed by full cross-validation procedure, providing to select the optimal number of factors. In the optimization step, the wavelength regions containing the most useful information were also selected and all the useless signals, due to interferences or noise, were discarded. For this aim, the authors developed a novel mathematical procedure, based on the absolute values of the component regression coefficients. This procedure was compared with the other ones reported in literature, by evaluating the application easiness and the improvement of the predictive ability of the models. The optimized models were compared by application to the analysis of synthetic mixtures and commercial pharmaceutical formulations, in order to establish their reliability in terms of accuracy and precision. According to these studies, multivariate calibration methods (PCR, PLS-1, PLS-2) coupled with derivative spectral data can be recommended as a very suitable choice to resolve severe overlapped absorption spectra of drug mixtures. This approach is simple in application, inexpensive,

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

requires an easy treatment of the samples and provides reliable analytical results. Fractional-order derivative spectroscopy has been developed by Li and Hu [7] to resolve the overlapped Lorentzian peak-signals. Resolutions are directly characterized by spectral parameters extracted from the overlapped peak-signals. For this purpose, using the Haar wavelet as a tool, the authors design a fractional-order differentiator to develop the fractional-order derivative spectroscopy. Wavelet transform (WT) has been rapidly developed during the last decade in various branches, e.g. signal processing, de-noising, spectral quantitative analysis, analysis of electrochemical noise data, photo-acoustic signal processing, resolving simulated overlapped spectra or flow-injection analysis. WT methods have been successfully introduced into analytical chemistry applications and have enriched the arsenal of chemometrics. WT has been established with the Fourier transform as a data-processing method in analytical chemistry. The main fields of application in analytical chemistry are related to de-noising, compression, variable reduction, and signal suppression. Starting from 1989, this new mathematical technique has been applied successfully for signal processing in chemistry. The number of publications related to the application of WT to manipulate chemical data has increased rapidly in the last years. WT was employed in different fields of analytical chemistry that include flow injection analysis, high performance liquid chromatography, infrared spectrometry, mass spectrometry, nuclear magnetic resonance spectrometry, ultraviolet–visible spectrometry and voltammetry. WT is a mathematical transformation for hierarchically decomposing functions. It led to a description of a function in terms of a coarse overall shape and details of a graded sequence. In the spectral studies, classical derivative and ratio spectra derivative methods were used for the quantitative resolving of the mixtures containing two or more compounds. Since the higher derivative process reduces the peak amplitude, the process of finding zero-crossing points is very difficult and the sensitivity of the method is decreasing. Particularly, the ratio spectra derivative method leads us to an infinite value of ratio spectra in some cases. For these reasons new methods should be discovered and applied to the analytical problems [8–10]. In this way, one promising method is WT, which was subjected to the optimization problem in multi-component analysis. Wavelet analysis was applied to removing non-constant, varying spectroscopic background in multivariate calibration. The importance of CWT comes from the signal transformation of the original one to the other form of signal giving opportunity of many families including Haar, Daubechies and Mexican hat function to obtain the best calibration signals. The selection of wavelet family is the most important step to get the best signal transformation for a given mixture. 3. Applications 3.1. Inorganic analysis DS is a very useful approach for determining the concentration of a single component in mixtures with overlapping spectra as it may eliminate interferences. So, DS has been used for the determination of the individual analyte in complex matrices. Derivative methods for the determination of metal ions through the formation of complexes with diverse ligands are given in Table 1. The research group of Devanna proposes the use of DS for the determination of different metal ions using isonicotinoyl hydrazones in which the interference zero-order method is eliminated in the first order derivative methods [12–16,18,19]. On the other hand, DS is used for the simultaneous determination of inorganic ions through the formation of their complexes with same organic ligand. DS methods are used for the quantitative analysis of binary mixtures because of its great sensitivity and selectivity as

3

well as a useful means of resolving two overlapping spectra and eliminating matrix interferences. Table 2 shows the analytical characteristics of diverse derivative procedures for simultaneous determination of binary mixtures of metal ions. Very recently, a new method for the simultaneous determination of Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ is developed by Han et al. [31], using mesotetra (3-methoxyl-4-hydroxylphenyl) porphyrin as reagent, by 2nd DS. By combining the spectrophotometer method and PeakFit software, the authors solved the problem of simultaneous determination of metal ion mixture, which was very difficult because of the overlapping problem. In pH 10.35 (Borax–NaOH buffer), using the previous cited reagent, micelle solution was formed after Tween-80 surfactant was added into the solution containing the five ions. The original absorption spectrum of the above complexes was obtained after heating in the boiling water for 25 min. The second-derivative absorption peaks of five metal–porphyrin complexes can be separated from the original absorption spectrum by using chemometric tool. The authors applied this method to determine the metal ions of the soil, the edible fungus and the Chinese medicine cassia seeds. The obtained results proved that this method is very simple and effective to simultaneous determination of metal ion mixture. Finally, the UV 2nd DS of nitric oxide (NO) complexed with horseradish peroxidase, in an anaerobic phosphate buffer solution, is measured and a new method is proposed by Qiang and Zhou [32] using second-order derivative spectral technique for the detection of NO in serum samples.

3.2. Pharmaceutical analysis In the last decades, DS has rapidly gained application in the field of pharmaceutical analysis to overcome the problem of interference, due to the substances other than analytes, commonly present in pharmaceutical formulations or for combination of two or more drug substances. DS has been successfully used as a quality control tool in pharmaceutical analysis for the simultaneous determination of drugs in multi-component formulations. This technique, accessible to most laboratories, offers an alternative means of enhancing the sensitivity and specificity in mixture analysis. The procedure is simple, rapid and does not require any preliminary separations or treatment of the samples. The analytical characteristics of DS methods for individual drugs determination are described in Table 3. During the last few decades, a great interest has been seen in the development of various novel drug delivery systems. In many of these formulations, surfactants like polysorbates (Tweens) and cosurfactants like propylene glycol and polyethylene glycol (PEG) are used. However, as those additives exhibit considerable absorbance at the wavelength of maximum absorbance of diazepam UVspectrometry method cannot be used to estimate the drug accurately in their presence. In this sense, Dastidar and Sa [38] present 1st DS as an accurate, precise, and simple method in comparison to conventional UV-spectrophotometry method for the estimation of diazepam in presence of Tween-20 and propylene glycol. UV–vis spectrophotometry represents a suitable method for the routine analysis of active ingredients in raw materials, since it is fast, easy to perform and does not require expensive instruments. Because its use is limited to the analysis of substances able to absorb light on the UV–vis domain, spectrophotometry is not useful for the direct determination of aminoglycosidic antibiotics, substances with weak light-absorbing capacity. Although the lack of chromophores in the chemical structure of aminoglycosides makes direct detection and quantification impossible, indirect spectrophotometry can be used in their case. Table 4 illustrates the analytical characteristics of numerous derivative methods for simultaneous determination of drugs.

[20]

[19]

0.02–0.6 Direct and 1st deriv.; zero-crossing method; HClO4 medium; 662.5 nm; simultaneous determination of U(VI) and Zr(IV) in mixed aqueous organic medium

0.7

Water, biological and pharmaceutical samples Environmental samples and alloys 0.13 0.1635–1.635 Direct and 1st deriv.; peak-zero method; pH 3.5; 473 and 540 nm, resp.

0.96 – Up to 12.26 1.19–11.9 1st deriv.; ratio spectrum zero-crossing method; pH 9.5; 622 nm 1st and 2nd deriv.; peak height method; pH 4; 436 and 441 nm, resp.

Zr

Zn

Alizarin complexone 2-hydroxy-3-methoxy-benzaldehyde-isonicotinoylhydrazone 3,5-dimethoxy-4-hydroxy-benzaldehydeisonicotinoyl-hydrazone Arsenazo-III Sr U

Ru Ru

Ni

Pb Mo

[17] [18]

[15] [16]

Synthetic samples of alloy and river waters Synthetic samples of alloy and river water samples Portland cement Rock and synthetic samples – –

0.004 0.294–2.94

0.202–4.04 0.505–6.06 pH 3; 402 nm 1st deriv.; peak height method; pH 4.5; 346 nm

[14]

[12] [13] 1 0.414–10.36 0.095–0.863

Synthetic mixtures and Algerian low gold ore solutions Synthetic alloy samples Foodstuffs, pharmaceutical samples and alloys Alloys b3

1st deriv.; zero-crossing method; 445 nm; selective extraction of gold in the presence of zinc; salting-out method using sodium chloride to cause phase separation 1st deriv.; peak height method; pH 10; 448 nm 1st and 2nd deriv.; pH 3; 433 and 457 nm, resp. without heating or extraction; more sensitive than the zero order method Direct and 1st deriv.; peak zero method; pH 9; 440 nm

Dithizone in presence of cetylpyridinium chloride as surfactant Diacetylmonoxime-4-hydroxybenzoylhydrazone Cinnamaldehyde-4-hydroxy-benzoylhydrazone in neutral surfactant Triton X-100 3,5-Dimethoxy-4-hydroxy-benzaldehydeisonicotinoyl-hydrazone Cinnamaldehyde isonicotinoylhydrazone Diacetyl-monoxime isonicotinoyl-hydrazone Au

0.857–5.142

Applications RSD (%) Linear range (μg mL− 1) Remarks Elements Reagents

Table 1 Analytical characteristic of derivative procedures for individual determination of metal ions.

[11]

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Ref.

4

Two simple and rapid spectrophotometric methods were developed by Belal et al. [87] for the resolution and analysis of the binary mixture of glyburide (GB) and metformin HCl (MF) in tablets. The first method, zero-crossing first derivative spectrophotometry, depends on measuring the first derivative values at 314.7 nm for GB and 228.6 nm for MF. The second method, ratio first derivative spectrophotometry, depends on measuring the amplitudes of the first derivative of the ratio spectra at 314.7 nm for GB and 238.0 nm for MF. The proposed methods were applied successfully to the assay of these drugs in commercial tablets. The zero-crossing derivative spectrophotometry is more rapid and simple than ratio derivative spectrophotometry; however the ratio derivative spectrophotometry has greater sensitivity and accuracy. These proposed methods could be regarded as useful alternative to the reported chromatographic and electrophoretic techniques in the routine quality control of pharmaceutical formulations, allowing qualitative and quantitative information to be simultaneously and rapidly achieved with a relatively inexpensive instrumentation. There are some methods described in the literature to the resolution of three components. So, two spectrophotometric methods are described by Abdel-Hay et al. [106] for the resolution of the threecomponent mixture of amiloride hydrochloride (AMD), hydrochlorothiazide (HCT) and timolol maleate (TIM). The first method involves the use of DS with the zero-crossing technique where AMD was determined using its 0D and 1D amplitudes at 365 and 385 nm, respectively, while HCT and TIM were determined by measuring the 3D amplitude at 265 nm and the 1D amplitude at 315.4 nm, respectively. The second method involves the application of the ratio-spectra zero-crossing first and second derivative spectrophotometry where two points have been used for the quantification of each compound. For the determination of AMD, HCT was used as a divisor and the 1DD and 2DD values at 299.4 and 311 nm, respectively, were plotted against AMD concentration; while – by using TIM as divisor – the 2DD amplitudes at 264.2 and 290 nm were found to be proportional to HCT concentration. TIM was assayed in the mixture using its 1DD amplitudes at 289.8 nm (Divisor was AMD) and 314.8 nm (Divisor was HCT). Two UV spectrophotometric methods have been developed by Pathak and Rajput [107] based on the first derivative spectrophotometry for simultaneous estimation of doxylamine succinate, pyridoxine hydrochloride, and folic acid in tablet formulations. In method 1, the concentrations of these drugs were determined by using linear regression equation. Method 2 is also based on first derivative spectrophotometry however simultaneous equations (Vierdot's method) were derived on derivative spectra. The first derivative amplitudes at 270.0, 332.8 and 309.2 nm were utilized for simultaneous estimation of these drugs respectively by both methods. In both methods, linearity was obtained in the concentration range 2.5–50, 1–40 and 1–30 μg mL − 1 for doxylamine succinate, pyridoxine hydrochloride, and folic acid respectively. Two spectrophotometric methods that do not require prior separation for simultaneous estimation of three drugs: paracetamol, nimesulide, and tizanidine in tablet formulation have been reported by Chandratrey and Sharma [108]. Method 1 was based on DS and the absorbances were measured at 229.5, 271, and 323.0 nm, being the zero crossing points for paracetamol, nimesulide and tizanidine, respectively. Method 2 is based on multi-wavelength spectroscopic method, absorbances of standard solutions were measured at 229.0 nm, 272.0 nm, 262.0 nm and 323.0 nm based on the statistical calculations and results of the sample solutions. First and second order DS methods with an application of base line to peak technique were used by Stolarczyk et al. [109] for the determination of active pharmaceutical ingredients at two wavelengths: fluphenazine (D1 at λ = 251 nm and λ = 265 nm, D2 at λ = 246 nm and λ = 269 nm), pernazine (D1 at λ = 246 nm and λ = 258 nm, D2 at λ = 254 nm and λ = 262 nm), haloperidol (D1 at λ = 235 nm and λ = 253 nm, D2 at λ = 230 nm and λ = 246 nm), and promazine

[30]

[28]

Synthetic and real samples Pd in hydrogenation catalysts and Ru in water samples Pd in hydrogenation catalyst and W in industrial waste water samples b4

0.1–10 0.1–11 0.21–12.78 0.25–13.42 0.53–6.40 0.92–11.40

–

–

[27] Alloy – 1–30 for both

[29]

Ferro-vanadium alloy, phosphor bronze, rice and [25] groundnut Ferro-vanadium alloy, phosphor bronze, rice and [25] groundnut Synthetic mixtures and commercial pharmaceutical [26] preparation 0.15 for both 0.15 0.39 – 0.635–3.81 0.558–3.348 0.635–3.81 0.509–3.06 2–12 for both

[24] Human hair and serum samples

Direct and 1st deriv.; in bis-2-ethyl hexyl sulfosiiccinate micellar solution; pH 2.5; 558 and 580 nm for Cu and 600 and 630 nm for iron 2-ketobutyric acid 2nd deriv.; zero-crossing method; pH 6.5; 387.2 nm for Cu and 440 nm for Fe thiosemicarbazone yellowish-green and blue complexes for Fe and Cu 2-ketobutyric acid 2nd deriv.; zero-crossing method; pH 5.5; 380 nm for Cu and 400 nm for V; blue and thiosemicarbazone yellow complexes for Cu and V 8-hydroxyquinoline 1st deriv.; zero crossing method at 388 and 487 nm for Fe in presence of Cu and 367 and 414 nm for Cu in presence of Fe; derivative ratio spectra method at 492 and 503 nm for Fe and 383 and 419 nm for Cu 6-(2-naphthyl)-2,3-dihydro-1,2,43rd deriv.; zero crossing method; basic media and extracted with chloroform; triazine-3-thione 472 nm for Cu and 501 nm for Ni 4-phenylpiperazine-carbodithioate 4th deriv. by zero crossing method and H-point standard addition method; pH 4; 440 and 465 nm for Cu and 350 and 365 nm for Pd; complexation in micellar media 2-hydroxy-3-methoxy benzaldehyde 2nd deriv.; pH 3; 445 nm for Pd and 385 nm for Ru thiosemicarbazone 3,4-dihydroxy-benzaldehyde 2nd deriv.; pH 5; 362 nm for Pd and 374 nm for W isonicotinoylhydrazone

1st deriv.; zero-crossing method and H-point standard addition method; pH 6; cetyltrimethylammonium bromide as surfactant at 25 º C Direct and 2nd deriv.; peak-zero method; pH 6; 455 and 424 nm, resp. 4-(2-pyridylazo) resorcinol

Cu Ni Cu Pd Pd Ru Pd W

2-acetylpyridine-4-methyl-3thiosemicarbazone 1-(2-pyridylazo)-2-naphthol

1st deriv.; zero-crossing method; pH 2; 422 and 426 nm, resp. Alizarin yellow

Al Fe Co Fe Co Ni Cu Fe Cu Fe Cu V Cu Fe

Alloys

[23]

0.43 0.67 –

[22] Synthetic binary mixtures and real samples

Alloys

b1.5 for both –

[21]

1.3–5.4 1.1-8.3 0.1–2.5 0.5–6 0.24–2.4 for both –

Applications Remarks Elements Reagents

Table 2 Analytical characteristics of derivative procedures for simultaneous determination of mixtures of metal ions.

Linear range (μg mL− 1)

RSD (%)

Ref.

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

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(D1 at λ = 246 nm and λ = 251 nm, D2 at λ = 255 nm and λ = 262 nm). Linear dependence of derivative values on analyte concentration is maintained in a range 3.12–44.80 μg mL − 1. 3.3. Stability-indicating methods A stability indicating method is a quantitative test method that can detect possible degradants with time and impurities of drug substance and drug products, normally using HPLC. Information of type and amount of degradation products over time is important for safety of drugs. DS was used for the stability-indicating determination of diverse drugs [110–124]. DS is a useful tool in the quantification of mixture of drugs. It could be even used as a stability-indicating technique for the analysis of drugs in presence of their degradation products, by solving the problem of the overlapping absorption bands. The photodegradation behavior of barnidipine (BAR) under stressing light and natural light was evaluated and the relative degradation pathways and kinetics under these irradiation conditions were compared by Ioele et al. [110]. BAR photodegradation was monitored by HPLC and zero-crossing DS. Adoption of the spectrophotometric analysis was justified by the authors due to easy recording of the spectra and the rapid interpretation of the data, which makes this technique very attractive for routine uses. On the other hand, zero-crossing is a powerful technique for the quantitative assay of the components of a mixture, particularly effective when a wide peak overlapping is present in the corresponding zero-order spectrum. Spectrophotometric studies of the degradation of biapenem were conducted by Cielecka-Piontek et al. [111] in order to develop a simple and fast analytical method, for quantification of biapenem in the presence of its degradation products. The method was based on the measurement of first-derivative amplitudes at zero crossing point (λ = 312 nm) and the peak-to-zero technique. Al-Arfaj et al. [112] describe a second DS method (at 291.2 nm which was the zero crossing point of candesartan in methanol) for the determination of candesartan cilexetil in the presence of its alkaline degradation product, candesartan. Four sensitive, selective and precise stability-indicating methods for the determination of clopidogrel bisulfate (CLP) in the presence of its alkaline degradate and in pharmaceutical formulations were developed and validated by Zaazaa et al. [113]. Method A is a second derivative spectrophotometric, which allows the determination of CLP in presence of its alkaline degradate at 219.6, 270.6, 274.2 and 278.4 nm (corresponding to zero-crossing of degradate). Method B is the first derivative of the ratio spectra spectrophotometric method, by measuring the peak amplitude at 217.6 and 229.4 nm using acetonitrile. Method C based on the determination of CLP by the bivariate calibration depending on simple mathematic algorithm which provides simplicity and rapidity; the method depends on quantitative evaluation of the absorbance at 210 and 225 nm. Method D is a TLC-densitometric, where CLP was separated from its degradate on silica gel plates using hexane:methanol:ethyl acetate (8.7:1:0.3, v/v/v). This method depends on the quantitative densitometric evaluation of thin layer chromatogram of CLP at 248 nm. A and B spectrophotometric methods are well-established techniques that are able to enhance the resolution of overlapping bands. These methods are simple, more convenient, less time consuming and economic stability indicating methods compared to other published LC methods. Kinetic studies of the decomposition of drugs using stability testing techniques are essential for the quality control of such products. In this work, the authors present a kinetic investigation of alkaline degradation of CLP. Bivariate calibration method provided simple and rapid determination of CLP with minimal sample and data manipulation. Finally, the advantages of TLC-densitometric method are that several samples can be run simultaneously using a small quantity

6

Table 3 Analytical characteristics of derivative procedures for individual determination of pharmaceutical compounds. Remarks

Linear range (μg mL− 1)

Precision (%)

Ref.

Atenolol

2.5–17.5

b6.04

[33]

1–125 6–32

b1.10 b2

[34] [35]

– 4–30

– –

[36] [37]

1–9 4–32 150–350

b1 – 0.65

[38] [39] [40]

2–14, 1–10 and 1–15, resp.

0.1530, 0.0177 and 0.0138, resp.

[41]

2–20, 1–15 and 1–25, resp. 0.004–0.008 (%)

0.1463, 0.0106 and 0.0159, resp. 2.52

[42] [43]

0.25–20 3–7; 6–14 40–80; 10–60 0.102–0.51

b1 in all cases 0.95 – 1.9

[44] [45] [46] [47]

0.5–25

b5 in all cases

[48]

Pioglitazone Racecadotril Ranitidine hydrochloride Ritonavir Tenofovir

Zero (276 nm), 1st (273, 276 and 285 nm), 2nd (276, 279, 282 and 287 nm) and 3rd (275, 278 and 281 nm) deriv. Zero (280 nm) and 2nd deriv. (227–232 nm) 1st deriv. (270.1 nm); in methanol with 0.35% polysorbate 20 at pH 6.5 phosphate buffer (1:9) solutions Colorimetric using folin ciocalteau reagent and 1st deriv. Zero in HCl 0.1 M (281 nm) and 1st deriv. in NaOH 0.1 M (difference between maxima at 266 nm and minima at 300 nm) 1st deriv. (260 nm); pH 7.4 2nd deriv. (247.4 nm) 1st deriv. (268 nm); Three methods of analysis (bioassay, first order derivative UV spectrophotometry and chromatographic methods); All methods showed to be specific, precise, accurate and linear in the concentration ranges tested. In both raw material and capsules Zero (430 nm), 1st (480 nm) and 2nd (500 nm) deriv.; by chelation with Pd(II); used as a catalyst in the preparation of wide range of drugs, essentially present in biological fluids Zero (545 nm), 1st (620 nm) and 2nd (660 nm) deriv.; by chelation with Cr(III) ion 3rd deriv. (281 nm); after modifying the molecule with o-phthalaldehyde. It was found that for the selected wavelength of 281 nm, the value of the third derivative depends on the analyte concentration and shows no interference with coexisting constituents. Zero (240 nm), 1st (224 nm), 2nd (241 nm) and area under curve method (235–245 nm) Zero (205 nm) and 1st (234 nm) deriv. 2nd (296 nm) and 3rd (290 nm) deriv. 1st (277 nm) deriv. Indirect DS method based on the capacity of neomycin to form in the presence of Cu2+ ions complex combinations with increased UV–vis light absorbing capacity. Optimum complex formation was found to take place in the presence of CuCl2.6H2O 1 mg mL− 1 when 20% methanol in bidistilled water was used as solvent. Zero (228.4 nm), 1st (306–330.2 nm), 2nd (321.2 nm), 3rd (270.4), 3rd (270.4–291 nm) and HPTLC UV ensitometry Zero (270.2 nm), 2nd (272–287.4 nm) deriv. and colorimetric method by ion par Zero (231 nm), 2nd (250 nm) and 3rd (240 nm) deriv. Zero (312 nm), 1st (332 nm) deriv. 2nd deriv. (222.3 nm) Zero (260 nm) and 1st (273 nm) deriv.

5–20; 2–12; 20–100 8–100 0.5–35.1 10–30 5–40

b4 in all cases – – b2 2

Tramadol hydrochloride Triclosan

Zero, 1st and 2nd deriv. (240–290 nm) 1st deriv.

10–100 7.5–45

– –

[49] [50] [51] [52] [53] [54] [55] [56]

Cabergoline Candesartan cilexetil Cefetamet pivoxil hydrochloride Cefuroxime axetil Diazepam Drotaverine hydrochloride Fluconazole

Gemifloxacin mesylate Gemifloxacin mesylate Gentamicin sulfate

Letrozole Losartan potassium Nebivolol hydrochloride Neomycin

Oxazepam

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

Compound

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

of mobile phase unlike HPLC, thus lowering analysis time and cost per analysis and provide high sensitivity and selectivity. Three methods for the determination of diacerein (DIA) in the presence of its alkaline degradation product were developed by Nebsen et al. [114]. Method A is a first DS at 322 nm, corresponding to zero crossing of degradate. Method B is a first derivative of the ratio spectra by measuring the peak amplitude at 352 nm. Method C is a TLC-densitometric, where DIA was separated from its degradate on silica gel plates using ethyl acetate:methanol:chloroform (8:1.5:0.5). This method depends on quantitative densitometric evaluation of thin layer chromatogram of DIA at 340 nm. Cielecka-Piontek and Jelinska [115] develop a spectrophotometric method of determination of doripenem in pure form and during degradation in the presence of opened β-lactam ring and dimeric products. The first-derivative with or without the substration technique, depending on formed products degradation was applied at 295 and 324 nm. Stability-indicative determination of ertapenem (ERTM) in the presence of its β-lactam open-ring degradation product, which is also the metabolite, was investigated by Hassan et al. [116]. The studied methods include first derivative, first derivative of the ratio spectra and bivariate analysis. Method A by applying the first derivative ultraviolet spectrophotometry; the method can solve the problem of spectral bands overlapping between ERTM and its degradant without sample pretreatment or extra separation steps. When the firstderivative spectra were examined, it was found that ERTM could be determined at 316 nm, where it's degradant has no contribution (zero crossing) allowing accurate determination of ERTM in presence of its degradant. Method B was derivative-ratio spectroscopy, a useful tool in quantification of drugs. It could be applied as a stabilityindicating method for the determination of ERTM in presence of its degradant. It could determine ERTM in the presence of higher degradation percentage than the first derivative method does. Linear calibration graphs were obtained for ERTM in concentration range of 4–60 μg mL − 1 by recording the peak amplitudes at 298 and 316 nm using 28 μg mL − 1 of the degradant as a divisor. Method C: For the bivariate determination of ERTM and its degradant, the wavelengths 215 and 297 nm were used. The bivariate calibration method may be competitive and in some cases even superior to commonly use DS methods as applied for the resolution of binary mixtures. The advantage of bivariate calibration method is its simplicity and the fact that derivatization procedures are not necessary. Unlike other chemometric techniques, there is no need for full spectrum information and no data processing is required. Reversed phase-high performance liquid chromatography (RPHPLC), thin layer chromatography (TLC) densitometry and first derivative spectrophotometry techniques are developed and validated by El-Moghazy et al. [117] as a stability-indicating assay of ezetimibe in the presence of alkaline induced degradation products. RP-HPLC method involves an isocratic elution on a Phenomenex Luna 5 μ C18 column using acetonitrile:water:glacial acetic acid (50:50:0.1 v/v/v) as a mobile phase at 235 nm. TLC densitometric method is based on the difference in Rƒ-values between the intact drug and its degradation products on aluminum-packed silica gel 60 F254 TLC plates as stationary phase with isopropanol:ammonia 33% (9:1 v/v) as a developing mobile phase. On the fluorescent plates, the spots were located by fluorescence quenching and the densitometric analysis was carried out at 250 nm. DS, the zero-crossing method, ezetimibe was determined using first derivative at 261 nm in the presence of its degradation products. The three methods could be easily performed for the analysis of ezetimibe in raw material and in pharmaceutical dosage forms without the interference of tablet excipients and their impurities, which makes them suitable for quality control analysis. Five methods were presented by Lotfy et al. [118] for the determination of famciclovir (FCV) in the presence of its alkaline-induced

7

degradation product. Method A uses first DS at 321 nm. Method B was the first derivative of the ratio spectra at 256 nm. Method C was based on the reaction of FCV with hydroxylamine to form hydroxamic acid that reacts with Fe3+ to form ferric hydroxamate that was measured at 503 nm. Method D was based on the separation of FCV from its degradation product on silica gel 60 F254, using chloroform:methanol (70:30) followed by densitometric measurement at 304 nm. Method E was based on a HPLC separation using an ODS column with a mobile phase of methanol: 50 mM dipotassium hydrogen phosphate (25:75, pH 3) at 304 nm. Markovic et al. [119] investigate the application of DS for the analysis of 2-phenoxypropionate ester of fluocinolone acetonide (FA-21PhP) solvolysis in ethanol/water solution using sodium hydrogen carbonate. method was used by the authors as a referent method. Due to the structural similarity of the solvolyte ethyl 2-phenoxypropionate (EtPhP) to the parent FA-21-PhP, particular consideration was paid to the selection of derivative order for efficient spectra resolution in solvolysis of ternary mixture. The application of zero-crossing technique in second-order derivative spectrophotometry was possible at only one analytical wavelength (274.96 nm) which was the joint zero-crossing point of parent ester and solvolyte EtPhP. The secondorder derivative assay of fluocinolone acetonide (FA) has a limitation in the initial stage of solvolysis due to lower sensitivity caused by means of FA amplitude satellite peak. It could be expected that DS in fourth-order spectra would be more efficient for in vivo analysis using esterases due to more substantial difference in zero-crossing points of parent ester and corresponding acid (PhPA). In this way FA is suppressed (binary mixture) and the sensitivity for parent ester assay would be higher due to central peak amplitude measurements. The HPLC method was used as a referent method and the peak area of parent ester (FA-21-PhP) was the signal for monitoring solvolytic reaction. Percentages of solvolysed FA-21-PhP, as well as the solvolytic rate constants, obtained by DS and HPLC confirmed that simple and fast DS method could be used as an alternative assay to HPLC method. Three stability-indicating methods were developed by Mohamed et al. [120] for the determination of racecadotril (RCT) in the presence of its alkaline degradation products. Method A was an HPLC method in which efficient chromatographic separation was achieved on a C18 analytical column and on a mobile phase of acetonitrile– methanol–water–acetic acid (52:28:20:0.1, v/v/v/v). Method B was a densitometric evaluation of thin-layer chromatograms of the drug using a mobile phase of isopropanol–ammonia (33%)-n-hexane (9:0.5:20, v/v/v); the chromatograms were scanned at 232 nm. Method C was based on the use of first DS at 240 nm. Three stability-indicating assay methods were developed by Abdel-Fattah et al. [121] for the determination of tropisetron in a pharmaceutical dosage form in the presence of its degradation products. The proposed techniques are HPLC, TLC, and first-DS. Acid degradation was carried out, and the degradation products were separated by TLC and were identified by IR, NMR, and MS techniques. The HPLC method was based on the determination of tropisetron in the presence of its acid-induced degradation product on an RP Nucleosil C18 column using methanol:water:acetonitrile:trimethylamine (65:20: 15:0.2, v/v/v/v) mobile phase at 285 nm. The TLC method was based on the separation of tropisetron and its acid-induced degradation products, followed by densitometric measurement of the intact spot at 285 nm. The separation was carried out on silica gel 60 F254 aluminum sheets using methanol:glacial acetic acid (22:3, v/v) mobile phase. DS method was based on the measurement of first-derivative amplitudes of tropisetron in H2O at the zero-crossing point of its acid-induced degradation product at 271.9 nm. A second DS method and a derivative ratio spectrum zero crossing method were used to determine raubasine and almitrine dismesylate in the presence of raubasine degradation product, using methanol as a solvent [122].

8

Table 4 Analytical characteristics of derivative procedures for simultaneous determination of pharmaceutical compounds. Compounds

Remarks

Linear ranges

Ref.

Aceclofenac Paracetamol Aceclofenac Tizanidine Acetaminophen Ascorbic acid Acetaminophen Tramadol Albendazole Praziquantel Almitrine dismesylate Raubasine Amitriptyline Chlordiazepoxide Amoxicillin Clavulanate Amoxicillin Cloxacillin Amoxicillin Ranitidine Antazoline Naphazoline Atorvastatin calcium Ezetimib Benzoic acid Salicylic acid Brucine Strychnine Caffeine Paracetamol Carvedilol Hydrochlorothiazide Cetrizine Phenylpropanolamine Chlordiazepoxide Imipramine Chlorhexidine Lidocaine Chlorphenamine maleate Dibucaine

Amplitude in 1st deriv. of the ratio spectra at 256 and 268 nm

–

[57]

1st deriv. by zero crossing method, at 250 and 313 nm

2–20 and 1–10 μg mL− 1

1st deriv. at 219 and 230 nm, reversed phase HPLC and HPTLC

1.5–24.2 and 1.8–21.1 μg mL 1 × 10− 5–6 × 10− 4 and 1 × 10− 5–10 × 10− 5 M 2 × 10− 6–3.5 × 10− 5 M for both drugs

[59] [60] [61]

10–24 and 6–20 μg mL− 1

[62]

1–20 and 2–24 μg mL

−1

for DS

[63]

−1

[64]

Zero (absorbance ratio and compensation), 1st deriv. and 1st deriv. ratio spectra

100–160 and 10–35 μg mL

Zero (absorbance ratio and compensation), 1st deriv. ratio spectra and reversed phase HPLC

60–140 μg mL− 1 for both drugs

[65]

1st deriv. at 334 nm for ranitidine, bivariate calibration algorithm (at 190 and 226 nm) and Vierortd method (at 208 and 312 nm) 1st deriv. ratio spectra at 235 and 227.2 nm

2 × 10− 6–2 × 10− 5 and 4 × 10− 6–6 × 10− 5 M

[66]

10–150 μM

[67]

1st deriv. ratio spectra at 266.6 and 262.2 nm and reverse phase HPLC

3–15 μg mL− 1 for both drugs and for both techniques

[68]

1st deriv. by zero crossing method, at 283 and 310 nm and reverse phase HPLC

10–30 and 20–60 μg mL− 1

[69]

1st deriv. at 256.4 and 265.4 nm

10–50 μg mL

−1

for both drugs −1

[70]

2nd deriv. by zero crossing method, at 288 and 260 nm

0.1–20 and 0.1–30 μg mL

1st deriv. at 248 and 285 nm

0.05–1.5 and 0.5–15 μg mL− 1

[72]

2nd deriv. at 238.08 nm and 271.39 nm and dual wavelength; in marketed brands of tablet

10–60 and 200–700 μg mL− 1

[73]

−1

[71]

1st deriv. at 219 and 231.5 nm

2–24 and 1–20 μg mL

1st deriv. at 290 nm and 2nd deriv. at 272 and 276 nm (peak to peak amplitude) PLS

5–9 and 160–480 μg mL− 1

[75]

1st deriv. at 274 and 312 nm; CLS, PLS, PCR. The detection limit for PLS and PCR were slightly higher than for 1st deriv. because 1st deriv. is zero order (from a chemometric view) and does not incorporate noise into the measurement, while the multivariate calibration methods consider the spectral ranges that do not have only analytic information since the noise has not been totally eliminated. 301.5 nm (zero crossing for ciprofloxacin) and 263 nm (zero crossing for ornidazole)

8 × 10− 7–3 × 10− 4 and 1.8 × 10− 6–3 × 10− 4 M

[76]

0–40 and 0–60 μg mL− 1

[77]

3rd deriv. at 316 and 226 nm and CWT. High amplitude in CWT method improves the sensitivity and having several zero cross-points can be used to eliminate probable interferences and diminishing the noise. 1st deriv. at 280 and 244 nm

5–60 and 1–8 μg mL− 1

[78]

2.5–15 and 120–720 μg mL− 1

[79]

[74]

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

Ciprofloxacin Ornidazole Cyproterone acetate Ethinyl estradiol Desloratadine Pseudoephedrine

Zero and derivative data (215–310 nm) using PCR and PLS chemometric methods 2nd deriv. by zero crossing method, at 308 and 285.7 nm 2nd deriv. at 327.5 and 223.2 nm and PCR, PLS, CLS chemometric methods of drugs dissolved in methanol–HCl solution 1st deriv. for raubasine and 1st deriv. ratio spectra for almitrine using methanol as solvent

[58] −1

Sulfamethoxazole Trimethoprin

Liquid chromatographic and two spectrophotometric methods, principal component regression and 1st deriv. at 247.8 and 240.2 nm Ratio spectra DS at 271.5 and 249 nm and direct spectrophotometry using simultaneous equation method at 287 and 258 nm 1st deriv. at 253.2 and 266.4 nm

2.4–40 and 60–260 μg mL− 1

[80]

–

[81]

9–45 and 6–30 μg mL

−1

[82]

−1

2nd deriv.

50–1000 μg mL

1st deriv. at 223.4 and 237.4 nm

2.5–15 μg mL− 1 for both drugs

[84]

1st deriv. at 237.6 and 248 nm

4–24 and 2–24 μg mL− 1

[85]

−1

[86]

[83]

1st deriv. at 265 and 219 nm

1–20 and 2–40 μg mL

Two 1st deriv. methods; in tablets (zero-crossing and ratio first derivative spectrophotometry) 1st deriv. at 282.0–290.2 and 277.4–287.8 nm; in liquid or solid dosage forms; combination of H-point standard addition methods and DS 1st deriv. at 332 and 244.6 nm

10–125 and 2–18 μg mL− 1

[87]

–

[88]

1 × 10

−5

–5 × 10

−5

M

[89] −1

1st deriv. at 334.6 and 294.6 nm

10–60 and 8–40 μg mL

1st deriv. by ratio spectra at 231.0 and 271.0 nm and zero crossing techniques at 257.8 and 240.2 nm

0.5–15 and 0.8–24 μg mL− 1

[91]

1st derive. at 233 and 243 nm. 2nd deriv. at 231 nm and 224 nm

1–6 and 0.75–5 μg mL− 1

[92]

[90]

−1

1st deriv. at 252.4 and 259.2 nm

4–20 and 10–50 μg mL

1st deriv. at 249 and 236 nm; in commercial formulations of imidacloprid, good agreement with the comparative HPLC–DAD procedure 1st deriv. at 288 and 238.5 nm

1.6–22.5 μg mL− 1 for both drugs

[94]

5–40 and 3–15 μg mL− 1

[95]

1st deriv. at 238.2 and 291.6 nm

5–30 and 10–60 μg mL

[93]

−1

[96]

−1

1st deriv. at 277.5 and 319 nm

10–50 and 20–80 μg mL

2nd deriv. at 237.7 and 233.2 nm

1.508 × 10− 6–15.08 × 10− 6 and 1.02 × 10− 6–10.2 × 10− 6

[98]

Zero, 1st and 2nd deriv. using peak-peak and peak-zero measurements

14–24 and 4–14 μg mL− 1

[99]

−1

Three spectrophotometric methods and one HPLC method; in tablets

1–10 and 5–50 μg mL

Three spectrophotometric methods (1st deriv at 218.3 nm, 245.6 nm); pure form and in pharmaceutical formulations; mean centring of the ratio spectra, allows the determination of both MZ and SP. 1st deriv. at 295 and 305 nm

5–25 μg mL− 1 for both drugs

1st deriv. at 266.8 and 382.2 nm; pH 7 for OTC; acetonitrile for OA extraction Three UV spectrophotometric methods: zero crossing derivative spectrophotometry at 284.0 nm for PHE and 241.2 nm for TPC, dual wavelength method at 260.8 nm and 268.2 nm for estimation of PHE and 245.4 nm and 271.8 nm for TPC and ratio spectra DS using amplitudes at 270.8 nm for PHE and 240.8 nm for TPC . 1st deriv. at 256 and 293 nm

[97]

[100] [101]

– 2.43 × 10

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

Diflucortolone valerate Isoconazole nitrate Domperidone Rabeprazole Domperidone Rabeprazole 2-Ethylhexyl-4-methoxycinnamate Oxybenzone Ezetimibe Rosuvastatin Ezetimibe Simvastatin Ezetimibe Simvastatin Glyburide Metformin Guaifenesin Theophylline Hydrochlorothiazide Losartan Hydrochlorothiazide Nebivolol Hydrochlorothiazide Olmesartan medoxomil Hydrochlorothiazide Triamterene Hypophyllanthin Phyllanthin Imidacloprid 6-chloronicotinic acid Itopride Pantoprazole Levocetirizine Montelukast Levofloxacin Ornidazole Lovastatin Simvastatin Mefenamic acid Meloxicam Metformin Rosiglitazone maleate Metronidazole Spiramycin Ofloxacin Tinidazole Oxolinic acid Oxytetracycline Phenylephrine Tropicamide

[102] −6

− 0.8 × 10

−4

25–125 and 4–20 μg mL

5–150 μM

and 1.88 × 10

−1

−5

− 0.1 × 10

−3

M

[103] [104]

[105]

9

10

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

Four sensitive, selective and precise stability indicating methods for the determination of isopropamide iodide (ISO) and trifluoperazine hydrochloride (TPZ) in their binary mixture and in presence of trifluoperazine oxidative degradate (OXD) were developed by Abbas et al. [123]. Method A is a DS, where ISO was determined by the first derivative at 226.4 nm while TPZ was determined by second derivative at 270.2 nm. Method B is the first derivative of the ratio spectra spectrophotometric method, ISO can be determined by measuring the peak amplitude at 227.4 nm using 5 μg mL − 1 of OXD as a divisor, while TPZ can be determined by measuring the peak amplitude at 249.2 and 261.4 nm using 15 μg mL − 1 of ISO as a divisor. Method C is the isoabsorptive spectrophotometric method. This method allows the determination of ISO and TPZ in their binary mixture by measuring total concentration of ISO and TPZ at their isoabsorptive point at 229.8 nm while TPZ concentration alone can be determined at 311.2 nm, then ISO concentration can be determined by subtraction. On the same basis TPZ can be determined in presence of ISO and OXD, where OXD concentration alone was determined by measuring the peak amplitude at 281.6 and 309.4 nm while total concentration of TPZ and OXD was determined at their isoabsorptive points at 270.2, 310.6 and 331.8 nm then TPZ concentration was determined by subtraction. Method D is the multivariate calibration techniques [the classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS)], using the information contained in the absorption spectra of ISO, TPZ and OXD mixtures. Derivative and derivative ratio methods were presented by Hassib et al. [124] for the determination of butamirate citrate, formoterol fumarate, montelukast sodium, and sodium cromoglycate. Using the second DS, butamirate citrate and formoterol fumarate were determined by measuring the peak amplitude at 260.4 and 261.8 nm, respectively, without any interference of their degradation products. Butamirate citrate degradation product, 2-phenyl butyric acid, was determined by the measurement of its second derivative amplitude at 246.7 nm where butamirate citrate displays zero crossing. Formoterol fumarate degradation product, desformyl derivative, could be evaluated through the use of the first derivative at peak amplitude of 264.8 nm where interference of formoterol fumarate is negligible. In the first mode, the zero-crossing technique was applied at 305 nm for the determination of montelukast sodium in the presence of its photodegradation product, cis-isomer. The derivative of ratio spectra of montelukast sodium and its cis-isomer were used to determine both isomers using the first derivative of the ratio spectra by measuring the amplitudes of the trough at 305 nm and the peak at 308 nm, respectively. The later technique was also used for the determination of a ternary mixture of sodium cromoglycate and its two degradation products using zero-crossing method. In the derivative ratio spectra of the ternary mixture, trough depths were measured at 271.6, 302.8 and 302.2 nm, using the second, the first, and the second mode to evaluate sodium cromoglycate, degradation product (1) and degradation product (2), respectively. 3.4. Analysis of biological compounds A first-order DS was applied for the determination of astaxanthin in Haematococcus pluvialis [125]. Ethyl acetate and ethanol (1:1, v/v) were found to be the best extraction solvent tested due to their high efficiency and low toxicity compared with nine other organic solvents. Astaxanthin coexisting with chlorophyll and β-carotene was analyzed by first-order DS in order to optimize the conditions for the determination of astaxanthin. The results show that when detected at 432 nm, the interfering substances could be eliminated. On the other hand, the statistical analysis between firstorder DS and HPLC by T-testing did not exceed their critical values, revealing no significant differences between these two methods. An and Liu establish a DS method for determining the content of adapalene in liposomes [126]. The first derivative was used to

determine the content of adapalene in liposome with wavelength at 279 nm. The excipients in the liposome did not interfere with the assay. The results of first DS were not significantly different from those of HPLC method as analyzed by Paired-Samples T test. Wang et al. [127] establish a second order DS method for the determination of the content of total iridoid glycoside in Gardenia jasminoides Ellis from different regions. The second order DS was performed at the wavelength of 263 nm. An indoor culture experiment was conducted by Zheng et al. to study the temporal change patterns of chlorophyll content and reflectance spectra of algae from Taihu Lake under different Fe(III) supply [128]. DS and red edge optical parameter were employed to quantitatively extract the algal spectral data, and correlation analysis was made between the algal spectral data and algal chlorophyll and Fe(III) contents. Based on these, the quantitative relationship of supplied Fe(III) concentration – algal chlorophyll content – algal spectra was established. The results showed that supplying appropriate concentration Fe(III) was conducive to the algal growth and chlorophyll synthesis. The studies developed by Silvestre et al. were an important step in the process for obtaining rice [129–131] and wheat flour [132,133] with low phenylalanine content. The authors optimize the enzymatic protein extraction and hydrolysis, using varied reaction conditions and the optimization of phenylalanine removal was studied using activated carbon as adsorbent and the efficiency of this procedure was evaluated by the second DS (from 250 to 280 nm). The area of a negative peak was used to calculate the amount of phenylalanine in the samples. In photodynamic therapy by irradiation with light, the porphyrin used as drugs induced DNA cleavage mainly via singlet oxygen mediated mechanism, and more rarely radical mediated mechanism. Ion [134] estimated that there are distinct interactions between DNA and 5,10,15,20-tetra-sulphonated-phenyl-porphyrin by means of UV–vis derivative spectrophotometry correlated with melting point, viscosity, and electrophoretic techniques for DNA evaluation. Magalhaes et al. [135] describe a high-throughput microplate protocol for assessing the partition coefficients (Kp) of drugs using hexadecylphosphocholine micelles as membrane models and DS as the detection technique. Kp of drugs between the phospholipid bilayer and the aqueous phase provides useful information in quantitative structure–activity relationship studies. The study developed by Brittes et al. [136] gathers a range of spectrophotometric and spectrofluorometric techniques to systematically monitor the effects of resveratrol on the biophysical properties of membrane model systems consisting of unilamellar liposomes of phosphatidylcholine with the ultimate goal of relating these effects with some of the well documented pharmacological properties of this compound. Kp of resveratrol between liposomes suspensions of phosphatidylcholine and aqueous solution was determined by DS. After recording absorption data, the second and third derivatives of spectra were determined to: eliminate the spectral interferences due to light scattered by the lipid vesicles; enhance the ability to detect minor spectral features and improve the resolution of bands. 3.5. Food analysis Anthocyanins (E 163) have been determined in red cabbage, blackberry, morello cherry, grape and sumac fruit by first order DS without using any separation or background correction techniques and reagents [137]. The method is based on the measurement of the distances between two extreme values, the maximum at 490.5 nm and the minimum at 550.2 nm (peak-to-peak amplitudes) in the first order derivative spectra of the extracts. Determination of vitamin C in fruits and commercial fruit juices was performed by DS without using any pre-separation or background correction techniques [138]. The method is based on the

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

measurement of peak-baseline amplitude in the second derivative spectra of the extracts at 267.5 nm. Second DS was used to determine the level and the heat stability of the three aromatic amino acids (tryptophan, tyrosine and phenylalanine) in bovine meat. Gatellier et al. [139] presents a method which measures the second derivative absorbance values at a wavelength specifically assigned to each aromatic amino acid with corrections for the interference from other amino acids at the same wavelength. The second derivative absorbance of each amino acid was measured by the vertical distance from baseline to the maximum negative peak of absorbance. Tryptophan exhibited two peaks, a major one at 288.5 nm and a minor one at 281 nm. Tyrosine exhibited a major peak at 282.5 nm and a smaller one at 275 nm. Finally, phenylalanine exhibited a major peak at 263.5 nm and a smaller one at 268 nm. The application of DS to resolve overlapping spectra and improve the sensitivity and selectivity of the colorimetric determination of urea in milk using diacetyl monoxime was presented by Nyanzi et al. [140]. With first-derivative spectrometry, the λmax of the colored complex was established to be 525 nm. The absorption band at λmax = 525 nm in normal absorption spectrometry was resolved into three clearly distinct spectral bands with minima at 497, 530, and 566 nm with second-derivative spectrometry. With the secondderivative technique, the depth of the trough of the strongest signal at 530 nm was used to determine urea in milk samples. Synthetic food dyes are usually added to processed foods to give and restore their desired esthetic quality. This aspect and the toxicological evidence justify quality control and the development of methodologies to quantify these food additives. In this way, Photoacoustic spectroscopy (PAS) was applied as a method to quantify dyed food samples, and was compared with first DS [141]. The dyes Brilliant Blue, Sunset Yellow and Tartrazine, which are common food additives, were employed for the comparisons. The absorption spectra of the samples and binary standard mixtures recorded between 400 and 700 nm, first derivative spectra were obtained and the signal at the zero-crossing points for the binary mixtures was measured, and, using appropriate working curves, the concentration of each dye in the different mixtures was determined. Also, PAS allowed the simultaneous determination of Brilliant Blue, Sunset Yellow and Tartrazine as binary mixtures in gelatin and juice powders, with a very good agreement between the values determined by using first DS. In the same way, Saad et al. [142] applied DS for the determination of tartrazine and sunset yellow, in three different kinds of foodstuffs: juice powders, flavored juices and soft drinks. Also, the mathematical methodologies such as the additivity principle, derivative spectrophotometry and multivariate technique (Partial Least Square Regression — PLSR) were studied in the simultaneous determination of Tartrazine and Sunset Yellow, extracted from natural wool [143]. These methodologies were evaluated and compared by the authors according to their prevision capacities. The best PLSR model (spectral range of 305 to 645 nm with data transformation by first derivative and two principal components) presented the lower RMSEP (Root Mean Square Error Prediction) value. Two methods were described by Ghaedi et al. [144] for simultaneous determination of glycyrrhizic acid (GA) and liquiritin (LQ) in pure and real sample extracted from licorice root without prior separation or purification. Method A was based on the first DS, with zero crossing and graphical (peak to baseline) measurement. The amplitudes at 272.3 and 316.2 nm were selected for the assay of GA and LQ, respectively. Method B was based on the Vierordt's method in the binary mixture at first derivative spectra that were calculated by using the absorbance measured at the same wavelengths. Methods of derivative spectrophotometry and zero order spectrophotometry were used to determine energizers in energy drinks. DS for the determination of caffeine and B vitamins in energy drinks after solid phase extraction was developed by Pieszko et al. [145]. Caffeine was determined in the mixture with B2 vitamin with zero-

11

crossing technique from the first derivative spectra (λ = 266.8 nm), and B3 in mixture with B6 vitamin from the second derivative spectra (λ = 280.1 nm). B12 vitamin has also been determined in a three component mixture with vitamins B3 and B6. Taurine in drinks has been determined from the basic spectra after derivatization with ninhydrin (λ = 570 nm). 3.6. Environmental analysis Chen et al. [146] develop a method with ratio spectrum-derivative spectrophotometry for the determination of chroma in pulping effluent without adjusting pH value and centrifugation or filtration, thus operating procedures are simplified, artificial error caused by human factors is minimized and accuracy of determination is improved. The same research group proposed a high-speed derivative spectrophotometry–chemometrics method for determination of chemical oxygen demand (COD) of pulping effluent [147]. In this method, based on the mathematical relationship between the multiwavelength derivative spectral signals and the known COD values of a set of pulping effluent samples, a calibration model is established using chemometrics software. With this model, the COD value of a certain pulping effluent can be easily predicted according to the multi-wavelength derivative spectral signals. A DS procedure was developed by Kaur et al. [148] for the determination of zinc(II) ethylenebisdithiocarbamate, Zineb, after formation of its blue colored complex with sodium molybdate in acidic medium. Zineb releases Zn 2+ and its dithiocarbamate unit, the latter forms a complex with sodium molybdate which is then extracted into methyl isobutyl ketone and determined by DS. The significant advantage of this method compared to the gas chromatographic methods is that it can be applied for the direct determination of Zineb in the presence of other dithiocarbamates like Ziram, Thiram and Ferbam. The molybdenum complex shows peaks at 670 nm and 956 nm, but the peak at 956 nm has much higher absorbance; hence all the measurements were made at this wavelength. The first derivative, second derivative, third derivative and fourth derivative curves were obtained and the 4th derivative spectra were found to be ideal. Dyes and pigments represent one of the problematic groups; they are emitted into wastewaters from various industrial branches, mainly from the dye manufacturing and textile finishing and also from food coloring, cosmetics and paper and carpet industries. Discharge of dye effluents into the natural streams may be toxic to the aquatic lives. For this reason, their determination was very important. DS was one of the most important techniques that can be used to determine the dye concentration. The binary mixtures of five textile dyes including yellow, scarlet, red, blue, and navy blue colors were analyzed by ratio spectra DS [149]. The absorption spectra of the binary mixtures, prepared in different ratios, were recorded between 400 and 700 nm. The obtained spectra were divided by a standard spectrum of each component of the binary mixtures, and then the derivative spectra were calculated. The amounts of dyes were determined by the measurements in the appropriate wavelengths in the range of 400–700 nm. Ratio spectra DS was introduced as a new approach for achieving the higher accuracy of determination of dye concentration in bicomponent dye solutions. The developed strategy could be applied in color industries where fine resolution of bicomponent dye mixtures is needed. Gozmen et al. [150] investigate the photocatalytic degradation of Basic Red 46 (BR46) and Basic Yellow 28 (BY28) dyes in binary mixture. Also, the effects of periodate ion concentration, irradiation time, initial pH and dye concentration on the photocatalytic degradation and mineralization of BR46, BY28 by UV/TiO2/IO4− system in single or binary mixture solutions were examined by the authors. First order derivative spectrophotometric method, which was a useful method to solve the overlapped spectra in multi-component systems,

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was used for the simultaneous analysis of BY28 and BR46 dyes in binary mixtures. BY28 dye could be determined at 380 nm in the presence of BR46, where the absorbance of BR46 was zero; and BR46 dye could be determined at 560 nm in the presence of BY28, where the absorbance of BY28 dye was zero. Almeida et al. [151] proposed the simultaneous determination of three dyes: Procion Yellow HE4R, Procion Red HE7B and Remazol Black 5; these are classified as reactive dyes and are used in the dyeing of cotton fibber; by first derivative spectrophotometry in samples of binary and ternary mixtures. Amplitudes of first-derivative spectra, from the baseline to the peak, at 395, 604 and 659 nm were proportional to the HE4R, HE7B and RB5 concentrations, respectively. The main objectives of the study developed by Gao et al. [152] were the simultaneous analysis of the Yellow 2G (Y2G) and Reactive Brilliant Red K-2G (RBR) dyes in binary solutions using the first-order derivative spectrophotometric method and the competitive biosorption of dyes onto inactive aerobic granules. Various mono- and multi-component isotherm models were applied to evaluate biosorption capacity and competition in the binary solutions. According to the derivative spectra, the Y2G could be determined at 433 nm, where the first-order derivative spectrum of RBR was zero; as at 512 nm the first-order derivative spectrum of Y2G was equal to zero, this wavelength could be selected for RBR. Principal component analysis (PCA) and DS techniques are used to improve the accuracy of Beer's law prediction of the concentrations in three-component dye mixtures [153]. In this work, 180 ternary mixtures of dyes were prepared by using Celasol Blue 4GL, Celasol Red 6BL and Celasol Yellow 4RL. The absorbance spectra of samples were measured from 400 to 700 nm. After computing the mathematical derivatives of a normal absorbance spectra, the first-order derivative spectra is confined with 16 wavelengths at 20-nm intervals from 400 to 700 nm to predict dye concentration by PCA-derivative technique. In this method, the 16 principal components are extracted from the first-order derivative absorbance spectra with 16 wavelengths. The first three principal components with highest Eigenvalue are used to predict the dye concentration. The normal- and first-order derivative absorbance spectra of 100 samples were selected for calibration, and others were used for evaluation performance of prediction. The performance of new method was compared with normal Beer's law. The biosorption of Acid Red 274 (AR274) and Acid Red 337 (AR337) dyes from single and binary solutions on Enteromorpha prolifera was investigated in a single stage batch system by Ozer and Turabik [154]. The zero order spectrophotometric method was used for the analysis of the AR274 and AR337 dyes from their single solutions while the first order derivative spectrophotometric method was applied for the biosorption from binary dyes solution. The single- and multi-component isotherm models were applied to the experimental data to determine the biosorbent capacity. AR274 dye was determined at 591 nm in the presence of AR337, where the absorbance of AR337 is zero, and AR337 dye was determined at 527 nm in the presence of AR274, where the absorbance of AR274 dye is zero. 3.7. Other analysis A monitoring method was developed for 2-naphthol to 1,1′-bi-2naphthol conversion reaction [155]. The simultaneous monitoring procedure is based on zero-crossing first DS in basic aqueous media. Zero-crossing first derivative wavelengths were 359.7 and 345.3 nm, respectively for 2-naphthol and 1,1′-bi-2-naphthol determinations. The quantitative results of HPLC and analysis of synthetic mixtures showed satisfactory compatibility with the results of the proposed derivative method. Liu et al. [156] report spontaneous vesicle formation from a cationic surfactant, dicetyl dimethyl ammonium chloride (DCDAC) and

its mixture with sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) in different ethanol–water mixed solvents, which have been demonstrated by the negative-staining transmission electric microscope (TEM) and the atomic force microscope (AFM) and the entrapment efficiency of the vesicles to all-trans retinoic acid (ATRA) was measured by the first order derivative spectrophotometry method at 362 nm. The biphasic nature of polymeric nanospheres prepared by the double emulsion method was exploited to co-encapsulate lipophilic and hydrophilic molecules [157]. ATRA was selected as a lipophilic drug model whereas calf thymus DNA was chosen as a watersoluble model. Simultaneous quantification of the loaded ingredients was achieved by a second derivative spectrophotometric technique. The experiments achieved showed that the second derivative absorbance was useful for the elimination of most interference. Hence, the spectra of the prepared mixtures were recorded, and the corresponding second derivative data were computed and plotted. With each mixture, the amplitude of the valley at 262 nm was measured for DNA determination in the presence of ATRA, whereas peak to valley values at 342 and 392 nm, respectively, was summed for the quantification of ATRA in the presence of DNA.

4. The derivative technique as a tool for green analytical chemistry Derivative spectroscopy is an analytical technique of great utility for extracting both qualitative and quantitative information from spectra or chromatograms composed of unresolved bands. This makes unnecessary the preparation of other samples to obtain spectra or chromatograms with a higher level of resolution and thus can achieve significant savings on products and solvents. Although derivative techniques were introduced more 50 years ago and have demonstrable advantages for the solution of specific analytical problems, this technique has been accepted only hesitantly, because of the initial lack of reasonably priced instrumentation and original limitation to the first derivative. However, the introduction of first electronic differentiation by a microcomputer interfaced with the spectrophotometer and more recently the use of a adequate computer for the mathematical treatment of derivative signal by means of an adequate algorithm makes possible the plotting of the first, second or higher order derivatives of a spectrum with respect to wavelength or a chromatogram with respect to time. Miniaturization of analytical methods and instrumentation has resulted in precisely controlled trace level analyses, and their high environmental compatibility owing to insignificant amount of solvent and reagent consumption, low waste production, and low operational cost. Most of the current analytical procedures consist of a sample preparation step, and quantitation by chromatography and spectrometry. Solvent extraction has been most widely used method for sample preparation. However, the classical mode of solvent extraction performed in a separatory funnel has inconveniences of unfavorable partition equilibria, formation of emulsions, necessity to use large volume of hazardous and ozone depleting organic solvents and difficulty in waste disposal. Miniaturization of extraction process by using microliter volumes of the organic solvent has avoided many of these problems, allowed new ways in which the sample pretreatment can be performed. UV–vis spectrophotometry is a mature analytical technique applied to many thousands of determinations owing to its simplicity, flexibility, low cost and convenience. Due to the widespread use of UV–vis spectrophotometers for routine analysis and as a result of the great demand to decrease the sample volume needed to perform a measurement, UV–vis micro-spectrophotometry has been developed [158].

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5. Conclusions Derivative spectrophotometry is an analytical technique of great utility for extracting both qualitative and quantitative information from spectra composed of unresolved bands by calculating and plotting one of the mathematical derivatives of a spectral curve. Therefore the derivative spectra (first to fourth-order) of the mixtures were checked to select a suitable spectrum to be used for the simultaneous determination of the components. Derivative techniques in spectroscopy often offer a powerful tool for a resolution enhancement, when signal overlaps or interference exists. Several specific signals were singled out for the components in the spectra of different derivative orders but the first-order derivative spectra seemed to be generally the most suitable for analytical aim. A derivative spectrum shows better resolution of overlapping bands than the fundamental spectrum and may permit the accurate determination of the λmax of the individual bands. Secondly, DS discriminates in favor of substances of narrow spectral bandwidth against broad bandwidth substances. All the amplitudes in the derivative spectrum are proportional to the concentration of the analyte provided that Beer's law is obeyed by the fundamental spectrum. DS offers a convenient solution to a number of analytical problems, such as resolution of multicomponent systems, removal of sample turbidity, matrix background and enhancement of spectral details and for eliminating the effect of baseline shifts and baseline tilts. Methods based on processing the spectral data could be applied to the simultaneous determination of compounds in mixtures without interference of each other. Chemometric methods are less expensive by comparison and they do not require sophisticated instrumentation and any prior separation step, but they need software for calibration and determination of the component of the mixture. On the other hand, the combined use of derivative spectrophotometry and chemometric techniques has demonstrated to be a highly convenient choice in the determination of multicomponent matrices presenting serious spectra overlapping, thanks to their common potential ability to exploit minor spectral features. So, Ultraviolet–visible spectral data can be transformed in creasing derivative orders so to obtain more useful information. Application of chemometric methods to derivative UV spectra can magnify the prediction ability of this spectrophotometric technique. The DS method has turnaround of a few minutes compared with other methods, such as HPLC. On the other hand, DS does not require in almost cases separation steps and the instruments used in the determination of analytes are relatively not expensive and sophisticated. It does not require an elaborate system and can be easily set up in manufacturing environment. Also, it is not labor-intensive, does not require higher skilled personnel, is cheap, is less time consuming, and, therefore, is very productive. Derivative techniques were applied for spectrophotometric data treatment, as a powerful and simple tool, to enhance the accuracy of both qualitative and quantitative analyses of mixtures. Such an approach is particularly helpful when the signal is weak or when different signals interfere conjointly.

References [1] F. Sanchez Rojas, C. Bosch Ojeda, J.M. Cano Pavon, Derivative ultraviolet–visible absorption spectrometry and its analytical applications, Talanta 35 (1988) 753–761. [2] C. Bosch Ojeda, F. Sanchez Rojas, J.M. Cano Pavon, Recent developments in derivative ultraviolet/visible absorption spectrophotometry, Talanta 42 (1995) 1195–1214. [3] C. Bosch Ojeda, F. Sanchez Rojas, Recent developments in derivative ultraviolet/visible absorption spectrophotometry, Anal. Chim. Acta 518 (2004) 1–24. [4] F. Sanchez Rojas, C. Bosch Ojeda, Recent development in derivative ultraviolet/visible absorption spectrophotometry: 2004-2008. A review, Anal. Chim. Acta 635 (2009) 22–44. [5] J. Krystek, Determination of analytical wavelength in derivative spectrophotometry, Instrum. Sci. Technol. 37 (2009) 82–88.

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[6] M. De Luca, F. Oliverio, G. Ioele, G. Ragno, Multivariate calibration techniques applied to derivative spectroscopy data for the analysis of pharmaceutical mixtures, Chemometr. Intell. Lab. Syst. 96 (2009) 14–21. [7] Y.L. Li, L. Hu, Fractional-order derivative spectroscopy for resolving overlapped lorenztian peak-signals, ICSP2010 Proceedings, 2010, pp. 211–214. [8] G. Ugurlu, N. Özaltin, E. Dinç, Spectrophotometric determination of risedronate sodium in pharmaceutical preparations by derivative and continuous wavelet transforms, Rev. Anal. Chem. 27 (2008) 215–233. [9] E. Dinç, G. Pektş, D. Baleanu, Continuous wavelet transform and derivative spectrophotometry for the quantitative spectral resolution of a mixture containing levamizole and triclabendazole in veterinary tablets, Rev. Anal. Chem. 28 (2009) 79–92. [10] E. Dinç, Y. Kadio lu, F. Demirkaya, D. Baleanu, Continuous wavelet transforms for simultaneous spectral determination of trimethoprim and sulphamethoxazole in tablets, J. Iranian Chem. Soc. 8 (2011) 90–99. [11] K. Belhamel, Selective extraction and determination of Au(III) by first-derivative spectrophotometry, J. Coord. Chem. 63 (2010) 4290–4298. [12] G.N. Reddy, K.B. Chandrasekhar, N. Devanna, K.N. Jayaveera, Derivative spectrophotometric determination of lead(II) using diacetylmonoxime-4hydroxybenzoylhydrazone, Asian J. Chem. 20 (2008) 2257–2263. [13] C.H.K. Devi, D.G. Krishna, N. Devanna, K.B. Chandrasekhar, Direct and derivative spectrophotometric determination of molybdenum(VI) in presence of micellar medium in food stuffs, pharmaceutical samples and in alloys using cinnamaldehyde-4-hydroxy benzoylhydrazone (CHBH), Res. J. Pharm. Biol. Chem. Sci. 1 (2010) 808–825. [14] K. Aruna Bai, G.V.S. Vallinath, K.B. Chandrasekhar, N. Devanna, Derivative spectrophotometric determination of nickel(II) using 3, 5-dimethoxy-4-hydroxy benzaldehyde isonicotinoyl hydrazone (DMHBIH), Rasayan J. Chem. 3 (2010) 467–472. [15] V.K. Kumar, M.R. Rao, K.B. Chandrasekhar, N. Devanna, Derivative spectrophotometric determination of ruthenium(III) using cinamaldehyde isonicotinoylhydrazone (CINH), Asian J. Chem. 20 (2008) 2197–2204. [16] G. Reddy Chandrasekhar, N. Devanna, K.B. Chandrasekhar, Derivative spectrophotometric determination of ruthenium(III) using diacetyl monoxime isonicotinoyl hydrazone (DMIH), Res. J. Chem. Environ. 15 (2011) 55–58. [17] K.A. Idriss, H. Sedaira, S.S. Ahmed, Determination of strontium and simultaneous determination of strontium oxide, magnesium oxide and calcium oxide content of portland cement by derivative ratio spectrophotometry, Talanta 78 (2009) 81–87. [18] M. Rameswara Rao, K. Hari, N. Devanna, K.B. Chandrasekhar, Derivative spectrophotometry determination of Uranium(VI) using 2-hydroxy-3methoxybenzaldehydeisonicotinoyl-hydrazone reagent, Asian J. Chem. 20 (2008) 1402–1410. [19] G.V.S. Vallinath, K.B. Chandra Sekhar, N. Devanna, Direct and derivative spectrophotometric determination of zinc(II) using 3,5-dimethoxy-4hydroxybenzaldehyde isonicotinoyl hydrazone (DMHBIH), Res. J. Pharm. Biol. Chem. Sci. 1 (2010) 739–749. [20] A.A. El-Sayed, M.M. Hamed, S.A. El-Reefy, Determination of micro-amounts of zirconium in mixed aqueous organic medium by normal and first-derivative spectrophotometry, J. Anal. Chem. 65 (2010) 1113–1117. [21] M.M. Seleim, M.S. Abu-Bakr, E.Y. Hashem, A.M. El-Zohry, Simultaneous determination of aluminum(III) and iron(III) by first-derivative spectrophotometry in alloys, J. Appl. Spectros. 76 (2009) 554–563. [22] H.R. Pouretedal, P. Sononi, M.H. Keshavarz, A. Semnani, Simultaneous determination of cobalt and iron using first-derivative spectrophotometric and Hpoint standard addition methods in micellar media, Chemistry 18 (2009) 22–35. [23] K. Vasudeva Reddy, D. Nagarjuna Reddy, K. Hussain Reddy, Derivative spectrophotometric determination of cobalt(II) and nickel(II) using 2-acetylpyridine-4-methyl-3-thiosemicarbazone (APMT), J. Chem. Pharmaceut. Res. 3 (2011) 835–839. [24] K.N. Ghasem, L. Saghatforoush, S. Ershad, Simultaneous determination of copper and iron in biological samples with l-(2-pvridylazo)-2-naphthol in anionic AOT micellar solution using derivative spectrophotometry, Asian J. Chem. 21 (2009) 2565–2572. [25] L.E. Attah, Second derivative spectrophotometry for simultaneous determination of iron(II) and copper(II) using 2-ketobutyric acid thiosemicarbazone, Indian J. Chem. Tech. 16 (2009) 351–356. [26] M.T. Alula, A.I. Mohamed, A.A. Bekhit, Simultaneous spectrophotometric determination of iron (II) and copper (II) in tablets by chemometric methods, Thai. J. Pharm. Sci. 34 (2010) 93–106. [27] M.B. Tehrani, E. Souri, Third Derivative Spectrophotometric method for simultaneous determination of copper and nickel using 6-(2-naphthyl)-2, 3-dihydro1,2,4-triazine-3-thione, E-Journal Chem. 8 (2011) 587–590. [28] V. Kaur, A.K. Malik, N. Verma, Simultaneous determination of Cu(II) and Pd(II) as 4-phenylpiperazinecarbodithioate complex using H-Point standard addition method and derivative spectrophotometry, Turk. J. Chem. 34 (2010) 295–305. [29] A.P. Kumar, P.R. Reddy, V.K. Reddy, Y.I. Lee, Simple and simultaneous method for determination of palladium(II) and ruthenium(III) using second-orderderivative spectrophotometry, Anal. Lett. 42 (2009) 84–93. [30] J. Srinivas, A.B.V. Kiran Kumar, T. Daniel Thangadurai, V. Suryanarayana Rao, Y.J. Yoo, Y.I. Lee, Non-extractive simultaneous spectrophotometric determination of trace quantities of palladium(II) and tungsten(VI), Anal. Lett. 44 (2011) 815–823. [31] Y. Han, Y. Li, W. Si, D. Wei, Z. Yao, X. Zheng, B. Du, Q. Wei, Simultaneous determination of Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ by using second-derivative spectrophotometry method, Spectrochim. Acta, Part A 79 (2011) 1546–1551.

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C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

[32] L. Quiang, J. Zhou, Determination of nitric oxide using horseradish peroxidise by UV second-order derivative spectrometry, Anal. Sci. 25 (2009) 1467–1470. [33] B. Yilmaz, Determination of atenolol in pharmaceutical preparation by zero-, first-, second- and third-order derivative spectrophotometric methods, Fabad J. Pharm. Sci. 33 (2008) 119–129. [34] D. Salman, A. Dogan, N.E. Basci, Spectrophotometric analysis of cabergoline in pharmaceutical preparations, Lat. Am. J. Pharm. 30 (2011) 304–310. [35] N.A. Charoo, M. Bashir, E. Abdalla, K.I.H. Ali, Determination of candesartan cilexetil in tablet dosage forms and dissolution testing samples by first derivative UV spectrophotometric method, Anal. Lett. 42 (2009) 2232–2243. [36] N.H. Vadia, N.B. Dobaria, V.B. Patel, conventional and advanced spectrophotometric methods for estimation of cefetamet pivoxil hydrochloride in bulk and in pharmaceutical formulation, Int. J. ChemTech. Res. 1 (2009) 286–290. [37] M.D. Game, D.M. Sakarkar, K.B. Gabhane, K.K. Tapar, Validated spectrophotometric methods for the determination of cefuroxime axetil in bulk drug and tablets, Int. J. ChemTech Res. 2 (2010) 1259–1262. [38] D.G. Dastidar, B. Sa, A comparative study of UV-spectrophotometry and first-order derivative UV-spectrophotometry methods for the estimation of diazepam in presence of tween-20 and propylene glycol, AAPS Pharm Sci Tech 10 (2009) 1396–1400. [39] B.P. Nagori, P. Khandelwal, S. Sharma, Second derivative spectrophotometric method for the estimation of drotaverine hydrochloride in tablet formulations, Indian Drugs 45 (2008) 798–800. [40] J.C.R. Correa, C. Reichman, H.R.N. Salgado, C.D. Vianna-Soares, Performance characteristics of high performance liquid chromatography, first order derivative UV spectrophotometry and bioassay for fluconazole determination in capsules, Quim. Nova 35 (2011) 530–534. [41] D. Madhuri, K.B. Chandrasekhar, N. Devanna, G. Somasekhar, Direct and derivative spectrophotometric estimation of gemifloxacin by chelation with palladium(II) ion, Rasayan J. Chem. 3 (2010) 159–165. [42] D. Madhuri, K.B. Chandrasekhar, N. Devanna, G. Somasekhar, Direct and derivative spectrophotometric estimation of gemifloxacinmesylate by chelation with Cr(III) ion, Rasayan J. Chem. 3 (2010) 9–15. [43] J. Krzek, H. Woltyńska, U. Hubicka, Determination of gentamicin sulphate in injection solutions by derivative spectrophotometry, Anal. Lett. 42 (2009) 473–482. [44] S.K. Acharjya, P. Mallick, P. Panda, K.R. Kumar, M.M. Annapurna, Spectrophotometric methods for the determination of letrozole in bulk and pharmaceutical dosage forms, J. Adv. Pharm. Tech. Res. 1 (2010) 348–353. [45] R. Bonfilio, L.B. Favoretto, G.R. Pereira, R.D.C.P. Azevedo, M.B. De Araújo, Comparative study of analytical methods by direct and first derivative UV spectrophotometry for evaluation of losartan potassium in capsules, Brazilian J. Pharm. Sci. 46 (2010) 147–155. [46] S.M. Malipatil, M. Deepthi, S.K. Patil, K. Jahan, Second and third order derivative spectrophotometric estimation of nebivolol hydrochloride in bulk and pharmaceutical dosage forms, Int. J. Pharm. Pharm. Sci. 3 (2011) 13–15. [47] B. Szaniszlo, C. Iuga, M. Bojita, Indirect determination of neomycin by derivative spectrophotometry, Farmacie 84 (2011) 398–401. [48] M. Koba, K. Koba, T. Baczek, Determination of oxazepam in pharmaceutical formulation by HPTLC UV-densitometric and UV-derivative spectrophotometry Methods, Anal. Lett. 42 (2009) 1831–1843. [49] S.T. Ulu, F.T. Elmali, UV-second derivative spectrophotometric and colorimetric methods for the determination, validation and thermogravimetric analysis of new oral antidiabetic pioglitazone in pure and pharmaceutical preparations, Anal. Lett. 42 (2009) 2254–2270. [50] C.N. Raju, G.D. Rao, R. Sikharam, UV and two derivative spectrometric methods for determination of racecadotril in tablet formulation, Biosci. Biotechnol. Res. Asia 5 (2008) 747–752. [51] A. Sokół, J. Karpińska, R. Talecka, B. Starczewska, Quantification of ranitidine hydrochloride in the presence of its decomposition product by spectrophotometric methods. Application for kinetic study, Acta Pol. Pharm. Drug Res. 68 (2011) 169–177. [52] C.L. Dias, A.M. Bergold, P.E. Fröehlich, UV-Derivative spectrophotometric determination of ritonavir capsules and comparison with LC method, Anal. Lett. 42 (2009) 1900–1910. [53] A.S. Atul, H.B. Charushila, J.S. Sanjay, Determination of tenofovir in pharmaceutical formulation by zero order and first order derivative UV-spectrophotometry methods, Res. J. Chem. Environ. 12 (2008) 49–50. [54] A.S. Atul, H.B. Charushila, J.S. Sanjay, Application of UV-spectrophotometric methods for estimation of tenofovir disoproxil fumarate in tablets, Pak. J. Pharm. Sci. 22 (2009) 27–29. [55] A. Kucuk, Y. Kadioglu, Determination of tramadol hydrochloride by using UV and derivative spectrophotometric methods in human plasma, Asian J. Chem. 23 (2011) 663–667. [56] L. Du, M. Li, Y. Jin, Determination of triclosan in antiperspirant gels by first-order derivative spectrophotometry, Pharmazie 66 (2011) 740–743. [57] A. Nikam, S. Pawar, S. Gandhi, Estimation of paracetamol and aceclofenac in tablet formulation by ratio spectra derivative spectroscopy, Indian J. Pharmaceut. Sci. 70 (2008) 635–637. [58] S.J. Gondane, M.M. Deshpande, M.P. Mahajan, S.D. Sawant, Spectrophotometric method development and validation for estimation of tizanidine and aceclofenac in bulk drug & tablet formulation, Int. J. ChemTech Res. 3 (2011) 620–624. [59] H. Khajehsharifi, Z. Eskandari, A. Asadipour, Application of some chemometric methods in conventional and derivative spectrophotometric analysis of acetaminophen and ascorbic acid, Drug Test. Anal. 2 (2010) 162–167.

[60] M.I. Toral, J. Rivas, M. Saldías, C. Soto, S. Orellana, Simultaneous determination of acetaminophen and tramadol by second derivative spectrophotometry, J. Chilean Chem. Soc. 53 (2008) 1543–1548. [61] C. Soto, D. Contreras, S. Orellana, J. Yañez, M.I. Toral, Simultaneous determination of albendazole and praziquantel by second derivative spectrophotometry and multivariated calibration methods in veterinary pharmaceutical formulation, Anal. Sci. 26 (2010) 891–896. [62] M.A. El-Sayed, Determination of binary mixture of raubasine and almitrine dismesylate by derivative spectrophotometry, Saudi Pharmaceut. J. 17 (2009) 62–69. [63] S. Patel, N.J. Patel, Spectrophotometric and chromatographic simultaneous estimation of amitriptyline hydrochloride and chlordiazepoxide in tablet dosage forms, Indian J. Pharmaceut. Sci. 71 (2009) 472–476. [64] V.T. Huong, V.D. Hoang, Simultaneous determination of amoxicillin and clavulanate in combined tablets by non-derivative and derivative UV spectrophotometric techniques, Int. J. Pharm. Tech. Res. 1 (2009) 1173–1181. [65] D.T. Giang, V.D. Hoang, Comparative study of RP-HPLC and UV spectrophotometric techniques for the simultaneous determination of amoxicillin and cloxacillin in capsules, J. Young Pharm. 2 (2010) 190–195. [66] J. Karpińska, A. Sokół, M. Rozko, Applicability of derivative spectrophotometry, bivariate calibration algorithm, and the Vierordt method for simultaneous determination of ranitidine and amoxicillin in their binary mixtures, Anal. Lett. 42 (2009) 1203–1218. [67] R. Hajian, N. Shams, I. Kaedi, Application of ratio derivative spectrophotometry for simultaneous determination of naphazoline and antazoline in eye drops, E-Journal Chem. 7 (2010) 1530–1538. [68] V. Patel, R. Baldha, D. Patel, Simultaneous determination of atorvastatin calcium and ezetimib by ratio spectra derivative spectrophotometry and reverse phase-high performance liquid chromatography, Asian J. Chem. 22 (2010) 2511–2517. [69] B.O. Silva, First derivative spectrophotometric and high performance liquid chromatographic simultaneous determination of benzoic and salicylic acids in pharmaceutical preparations, Niger. Q. J. Hosp. Med. 18 (2008) 92–95. [70] B. Ganesan, P. Perumal, V. Manickam, S.R. Srikakolapu, S.D. Gotteti, L.S. Thirumurthy, Simultaneous determination of strychnine and brucine in herbal formulation by UV derivative spectrophotometry, Int. J. Pharm. Tech. Res. 2 (2010) 1528–1532. [71] H. Tavallali, M. Salami, Simultaneous determination of caffeine and paracetamol by zero-crossing second derivative spectrophotometry in pharmaceutical preparations, Asian J. Chem. 21 (2009) 1949–1956. [72] M. Sultan, Simultaneous determination of carvedilol and hydrochlorothiazide in tablets by derivative spectrophotometric and HPLC methods, Asian J. Chem. 20 (2008) 2283–2292. [73] R.P. Patel, A.F. Mehta, Estimation of cetrizine hydrochloride & phenylpropanolamine hydrochloride in combined dosage form by 2nd order derivative spectrophotometry and dual wavelength spectroscopic method, IJPI's J. Anal. Chem. 1 (2010) 1–9. [74] S. Patel, N.J. Patel, S.A. Patel, Simultaneous spectrophotometric estimation of imipramine hydrochloride and chlordiazepoxide in tablets, Indian J. Pharmaceut. Sci. 71 (2009) 468–472. [75] O.A. Donmez, A. Bozdogan, G. Kunt, Y. Div, Spectrophotometric multicomponent analysis of a mixture of chlorhexidine hydrochloride and lidocaine hydrochloride in pharmaceutical formulation using derivative spectrophotometry and partial least-squares multivariate calibration, J. Anal. Chem. 65 (2010) 30–35. [76] C. Soto, D. Contreras, M.I. Toral, L. Basaez, J. Freerc, Simultaneous determination of dibucaine and chlorphenamine maleate using different mathematical spectrophotometric approaches, J. Chilean Chem. Soc. 54 (2009) 113–118. [77] S.B. Wankhede, V.S. Gadewar, V. Thombre, S.S. Chitlange, Derivative spectrophotometric method for the simultaneous determination of ciprofloxacin and ornidazole in tablet dosage form, Indian Drugs 45 (2008) 426–429. [78] M.R. Sohrabi, P. Abdolmaleki, E.A. Esmaeili, Simultaneous spectrophotometric determination of cyproterone acetate and ethinyl estradiol in tablets using continuous wavelet and derivative transform, Spectrochim. Acta. Part A 77 (2010) 107–111. [79] S. Caglar, S.E. Toker, Simultaneous determination of desloratadine and pseudoephedrine sulphate in tablets by high performance liquid chromatography and derivative spectrophotometry, Rev. Anal. Chem. 30 (2011) 145–151. [80] E. Karacan, M.G. Çaĝlayan, I.M. Palabiyik, F. Onur, Liquid chromatographic and spectrophotometric determination of diflucortolone valerate and isoconazole nitrate in creams, J. AOAC Int. 94 (2011) 128–135. [81] R.G. Baldha, B. Patel Vandana, M. Bapna, Simultaneous spectrophotometric estimation of rabeprazole sodium and domperidone in combined dosage forms, Int. J. Pharm. Tech. Res. 2 (2010) 1563–1568. [82] A.H. Patel, J.K. Patel, K.N. Patel, Development and validation of derivative spectrophotometric method for simultaneous estimation of domperidone and rabeprazole sodium in bulk and dosage forms, Int. J. Pharm. Sci. 2 (2010) 464–469. [83] H.M. Chawla, S. Mrig, Simultaneous quantitative estimation of oxybenzone and 2-ethylhexyl-4-methoxycinnamate in sunscreen formulations by second order derivative spectrophotometry, J. Anal. Chem. 64 (2009) 585–592. [84] A.K. Gajjar, V.D. Shah, Simultaneous estimation of rosuvastatin and ezetimibe by ratio spectra derivative spectrophotometry method in their fixed dosage forms, Int. J. Pharm. Tech. Res. 2 (2010) 404–410. [85] K. Anandakumar, K. Kannan, T. Vetrichelvan, Simultaneous determination of simvastatin and ezetimibe in tablet formulation by derivative spectrophotometry, Indian J. Pharm. Educ. Res. 42 (2008) 122–126.

C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16 [86] E. Souri, M. Amanlou, Development and validation of a derivative spectrophotometric method for simultaneous determination of simvastatin and ezetimibe, E-Journal Chem. 7 (2010) S197–S202. [87] F.F. Belal, M.K.S. El-Din, F.A. Aly, M.M. Hefnawy, M.I. El-Awady, Spectrophotometric analysis of a mixture of glyburide and metformin hcl in pharmaceutical preparations, Der Pharma Chemica 3 (2011) 53–64. [88] R. Hajian, N. Shams, Z. Davarpanah, Combination of first derivative spectrophotometry and H-point standard addition method for simultaneous determination of guaifenesin and theophylline in cough syrup, E-Journal Chem. 8 (2011) 966–976. [89] M.I. Toral, S. Orellana, M. Saldías, C. Soto, Strategies used to develop analytical methods for simultaneous determination of organic compounds by derivative spectrophotometry, Quim. Nova 32 (2009) 257–262. [90] D.A. Shah, K.K. Bhatt, R.S. Mehta, S.L. Baldania, Determination of nebivolol hydrochloride and hydrochlorothiazide in tablets by first-order derivative spectrophotometry and liquid chromatography, J. AOAC Int. 91 (2008) 1075–1082. [91] A.R. Rote, P.D. Bari, Ratio spectra derivative and zero-crossing difference spectrophotometric determination of olmesartan medoxomil and hydrochlorothiazide in combined pharmaceutical dosage form, AAPS Pharm. Sci. Tech. 10 (2009) 1200–1205. [92] K. Mohammadpour, M.R. Sohrabi, A. Jourabchi, Continuous wavelet and derivative transform applied to the overlapping spectra for the quantitative spectrophotometric multi-resolution of triamterene and hydrochlorothiazide in triamterene-H tablets, Talanta 81 (2010) 1821–1825. [93] P. Rai, P. Patil, S.J. Rajput, Simultaneous determination of phyllanthin and hypophyllanthin in herbal formulation by derivative spectrophotometry and liquid chromatography, Pharmacogn. Mag. 4 (2009) 151–158. [94] V.J. Guzsvány, Z.J. Papp, S.D. Lazić, F.F. Gaál, L.J. Bjelica, B.F. Abramović, A rapid spectrophotometric determination of imidacloprid in selected commercial formulations in the presence of 6-chloronicotinic acid, J. Serb. Chem. Soc. 74 (2009) 1455–1465. [95] D. Bageshwar, A. Pawar, V. Khanvilkar, V. Kadam, Simultaneous determination of pantoprazole sodium and itopride hydrochloride in pharmaceutical dosage form by first order derivative UV spectrophotometry, Asian J. Pharm. Clin. Res. 3 (2010) 221–223. [96] A.R. Rote, V.S. Niphade, Determination of montelukast sodium and levocetirizine dihydrochloride in combined tablet dosage form by HPTLC and first-derivative spectrophotometry, J. Liq. Chrom. Relat. Tech. 34 (2011) 155–167. [97] D. Nagavalli, R. Rajeevkumar, P. Kumar, T. Devi, Derivative spectrophotometric estimation of levofloxacin hemihydrate and ornidazole, Int. J. Chem. Tech. Res. 2 (2010) 2145–2149. [98] I. Draghici, A. Nedelcu, C.M. Monciu, C. Aramc, Derivative spectrometry in the assay of simvastatin and lovastatin, Farmacia 56 (2008) 5–14. [99] A. Pomykalski, H. Hopkała, Comparison of classic and derivative UV spectrophotometric methods for quantification of meloxicam and mefenamic acid in pharmaceutical preparations, Acta Pol. Pharm. Drug Res. 68 (2011) 317–323. [100] A. Önal, Spectrophotometric and HPLC determinations of anti-diabetic drugs, rosiglitazone maleate and metformin hydrochloride, in pure form and in pharmaceutical preparations, Eur. J. Med. Chem. 44 (2009) 4998–5005. [101] F.I. Khattab, N.K. Ramadan, M.A. Hegazy, N.S. Ghoniem, Simultaneous determination of metronidazole and spiramycin in bulk powder and in tablets using different spectrophotometric techniques, Drug Test. Anal. 2 (2010) 37–44. [102] S.V. Gandhi, J.V. Shah, A.D. Nikam, V. Vaidyanathan, Estimation of ofloxacin and tinidazole in tablet formulation by ratio spectra derivative spectroscopy, Indian J. Pharm. Educ. Res. 42 (2008) 70–73. [103] M.I. Toral, S.L. Orellana, C.A. Soto, P. Richter, Extraction and determination of oxytetracycline hydrochloride and oxolinic acid in fish feed by derivative spectrophotometry of first order, Food Anal. Meth. 4 (2011) 497–504. [104] S. Sardana, R.C. Mashru, Simultaneous determination of phenylephrine hydrochloride and tropicamide in ophthalmic dosage form with three rapid derivative spectrophotometric methods, J. Chilean Chem. Soc. 55 (2010) 515–518. [105] R. Hajian, R. Haghighi, N. Shams, Combination of ratio derivative spectrophotometry with simultaneous standard additions method for determination of sulfamethoxazole and trimethoprim, Asian J. Chem. 22 (2010) 6569–6579. [106] M.H. Abdel-Hay, A.A. Gazy, E.M. Hassan, T.S. Belal, Derivative and derivative ratio spectrophotometric analysis of antihypertensive ternary mixture of amiloride hydrochloride, hydrochlorothiazide and timolol maleate, J. Chin. Chem. Soc. 55 (2008) 971–978. [107] A. Pathak, S. Rajput, Simultaneous derivative spectrophotometric analysis of doxylamine succinate, pyridoxine hydrochloride and folic acid in combined dosage forms, Indian J. Pharmaceut. Sci. 70 (2008) 513–517. [108] A. Chandratrey, R. Sharma, Simultaneous spectrophotometric estimation and validation of three component tablet formulation containing paracetamol, nimesulide and tizanidine, Indian J. Chem. Technol. 17 (2010) 229–232. [109] M. Stolarczyk, A. Apola, J.A.N. Krzek, A. Sajdak, Validation of derivative spectrophotometry method for determination of active ingredients from neuroleptics in pharmaceutical preparations, Acta Pol. Pharm. Drug Res. 66 (2009) 351–356. [110] G. Ioele, F. Oliverio, I. Andreu, M. De Luca, M.A. Miranda, G. Ragno, Different photodegradation behavior of barnidipine under natural and forced irradiation, J. Photochem. Photobiol A: Chem. 215 (2010) 205–213. [111] J. Cielecka-Piontek, A. Lunzer, A. Jelińska, Stability-indicating derivative spectrophotometry method for the determination of biapenem in the presence of its degradation products, Cent. Eur. J. Chem. 9 (2011) 35–40. [112] N.A. Al-Arfaj, W.A. Al-Onazi, A.M. El-Brashy, Spectrophotometric determination of candesartan cilexetil in presence of its alkaline induced degradation product, Asian J. Chem. 23 (2011) 1696–1700.

15

[113] H.E. Zaazaa, S.S. Abbas, M. Abdelkawy, M.M. Abdelrahman, Spectrophotometric and spectrodensitometric determination of clopidogrel bisulfate with kinetic study of its alkaline degradation, Talanta 78 (2009) 874–884. [114] M. Nebsen, M.K. Abd El-Rahman, M.Y. Salem, A.M. El-Kosasy, M.G. El-Bardicy, Stability-indicating spectrophotometric and spectrodensitometric methods for the determination of diacerein in the presence of its degradation product, Drug Test. Anal. 3 (2011) 221–227. [115] J. Cielecka-Piontek, A. Jelińska, The UV-derivative spectrophotometry for the determination of doripenem in the presence of its degradation products, Spectrochim. Acta, Part A 77 (2010) 554–557. [116] N.Y. Hassan, E.M. Abdel-Moety, N.A. Elragehy, M.R. Rezk, Selective determination of ertapenem in the presence of its degradation product, Spectrochim. Acta Part A 72 (2009) 915–921. [117] S.M. El-Moghazy, M.A. El-Azem Mohamed, M.F. Mohamed, N.F. Youssef, Development and validation of HPLC, TLC and derivative spectrophotometric methods for the analysis of ezetimibe in the presence of alkaline induced degradation products, J. Chin. Chem. Soc. 56 (2009) 360–367. [118] H.M. Lotfy, M.M.A. El-Moneim Abosen, M.G. EL-Bardicy, Stability-indicating methods for the determination of famciclovir in the presence of its alkaline-induced degradation product, Drug Test. Anal. 2 (2010) 188–199. [119] B. Markovic, S. Vladimirov, O. Cudina, V. Savic, K. Karljikovic-Rajic, An application of second-order UV-derivative spectrophotometry for study of solvolysis of a novel fluocinolone acetonide ester, Spectrochim. Acta Part A 75 (2010) 930–935. [120] A.O. Mohamed, M.M. Fouad, M.M. Hasan, S.A. Abdel Razeq, Z.A. Elsherif, Stability-indicating methods for the determination of racecadotril in the presence of its degradation products, Biosci. Trends 3 (2009) 247–252. [121] L.S. Abdel-Fattah, Z.A. El-Sherif, K.M. Kilani, D.A. El-Haddad, HPLC, TLC, and first-derivative spectrophotometry stability-indicating methods for the determination of tropisetron in the presence of its acid degradates, J. AOAC Int. 93 (2010) 1180–1191. [122] M.A. El-Sayed, Stability-indicating methods for the determination of a mixture of almitrine and raubasine by derivative spectrophotometry, Drug Test. Anal. 1 (2009) 279–285. [123] S.S. Abbas, H.E. Zaazaa, M. Abdelkawy, M.M. Abdelrahman, Spectrophotometric determination of isopropamide iodide and trifluoperazine hydrochloride in presence of trifluoperazine oxidative degradate, Drug Test. Anal. 2 (2010) 168–181. [124] S.T. Hassib, A.A. El-Zaher, M.A. Fouad, Validated stability-indicating derivative and derivative ratio methods for the determination of some drugs used to alleviate respiratory tract disorders and their degradation products, Drug Test. Anal. 3 (2011) 306–318. [125] L.X. Juan, W.Y. Hua, Z.L. Zhao, S. Xiao, Z.A. Mei, A. Xin, Determination of astaxanthin in haematococcus pluvialis by first-order derivative spectrophotometry, J. AOAC Int. 94 (2011) 1752–1757. [126] Y.C. An, L.P. Liu, Determination of adapalene content in liposomes by first derivative uv spectrophotometry, Chinese J. New Drugs 19 (2010) 534–536. [127] L. Wang, X. Wang, S. Wang, T. Zhou, G. Fan, Determination of the content of total iridoid glycoside in Gardenia jasminoides Ellis by second order derivative spectrophotometry, Pharmaceut. Care Res. 10 (2010) 205–207. [128] T.H. Zheng, Y. Shi, G.Y. Chi, X. Chen, Effects of Fe(III) on the growth and spectral characteristics of algae, Chinese J. Ecol. 29 (2010) 2471–2476. [129] M.P.C. Silvestre, C.R. Vieira, M.R. Silva, R.L. Carreira, V.D.M. Silva, H.A. Morais, Protein extraction and preparation of protein hydrolysates from rice with low phenylalanine content, Asian J. Sci. Res. 2 (2009) 146–154. [130] M.P.C. Silvestre, C.R. Vieira, M.R. Silva, M.C. Silva, C.O. Lopes Jr., V.D.M. Silva, Use of an enzymatic process for extracting and hydrolyzing rice proteins aiming at phenylalanine removal, Int. J. Food Eng. 5 (2009) 1–11. [131] R.L. Carreira, C.S. Ramos, L.A. Mundim, M.R. Silva, V.D.M. Silva, M.P.C. Silvestre, Effect of enzyme type, mode of enzyme action and temperature on the obtention of low phenylalanine hydrolysates from wheat flour, Am. J. Food Tech. 4 (2009) 71–78. [132] R.L. Carreira, V.D.M. Silva, J.N. Januário, M.J.B. De Aguiar, A.L.P. Starling, M.P.C. Silvestre, Action of enzymatic factors in obtaining protein hydrolysates from wheat flour with low phenylalanine, Brazilian J. Pharm. Sci. 45 (2009) 93–98. [133] R.L. Carreira, C.S. Ramos, A.B. de Vasconcelos, M.M. Santoro, M.P.C. Silvestre, Effect of hydrolytic parameters in obtaining of protein hydrolysates of wheat flour with low phenylalanine content, Cienc. Technol. Aliment. 30 (2010) 152–157. [134] R.M. Ion, Derivative UV-Vis spectrophotometry for porphyrins interactions in photodynamic therapy, Anal. Lett. 43 (2010) 1277–1286. [135] L.M. Magalhães, C. Nunes, M. Lúcio, M.A. Segundo, S. Reis, J.L.F.C. Lima, High-throughput microplate assay for the determination of drug partition coefficients, Nat. Protoc. 5 (2010) 1823–1830. [136] J. Brittes, M. Lúcio, C. Nunes, J.L.F.C. Lima, S. Reis, Effects of resveratrol on membrane biophysical properties: relevance for its pharmacological effects, Chem. Phys. Lipids 163 (2010) 747–754. [137] D. Şakar, G.K. Karaoglan, G. Gümrükçü, M.Ü. Özgür, Determination of anthocyanins in some vegetables and fruits by derivative spectrophotometric method, Rev. Anal. Chem. 27 (2008) 235–249. [138] N.Z. Blagojeviæ, V.L. Vukašinoviæ-Pešiæ, Determination of vitamin C in fruits and commercial fruit juices by derivative spectrophotometry, Res. J. Chem. Environ. 12 (2008) 18–22. [139] P. Gatellier, A. Kondjoyan, S. Portanguen, E. Grève, K. Yoon, V. Santé-Lhoutellier, Determination of aromatic amino acid content in cooked meat by derivative spectrophotometry: implications for nutritional quality of meat, Food Chem. 114 (2009) 1074–1078.

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C. Bosch Ojeda, F. Sanchez Rojas / Microchemical Journal 106 (2013) 1–16

[140] S.A. Nyanzi, M. Isiko, F. Kateregga, W. Schwack, Second-derivative spectrometric determination of urea in milk using the diacetyl monoxime reagent, J. AOAC Int. 93 (2010) 485–491. [141] T.M. Coelho, E.C. Vidotti, M.C. Rollemberg, A.N. Medina, M.L. Baesso, N. Cella, A.C. Bento, Photoacoustic spectroscopy as a tool for determination of food dyes: comparison with first derivative spectrophotometry, Talanta 81 (2010) 202–207. [142] A. Saad, S. Nazira, A. Rasha, Determination of tartrazine and sunset yellow in foodstuffs by derivative spectrophotometric method, Asian J. Chem. 23 (2011) 1825–1828. [143] M.E. dos Santos, I.M. Demiate, N. Nagata, Simultaneous determination of tartrazine and sunset yellow in food by spectrophotometry UV–VIS and multivariate calibration methodology, Cienc. Technol. Aliment. 30 (2010) 903–909. [144] A. Ghaedi, S.S. Madaeni, M.R. Sohrabi, M. Khosravi, Simultaneous determination of glycyrrhizic acid and liquiritin in licorice root using first derivative spectrophotometric and Vierordt's method, Fresen. Environ. Bull. 20 (2011) 1406–1413. [145] C. Pieszko, I. Baranowska, A. Flores, Determination of energizers in energy drinks, J. Anal. Chem. 65 (2010) 1228–1234. [146] H. Chen, Y. Chen, H. Zhan, S. Fu, Determination of chroma in pulping effluent by ratio spectrum-derivative spectrophotometry, Environ. Prog. Sustain. Energy 29 (2010) 342–348. [147] H.L. Chen, Y.C. Chen, H.Y. Zhan, S.Y. Fu, Determination of pulping effluent cod using derivative spectrophotometry–chemometrics method, Huanan Ligong Daxue Xuebao 37 (2009) 150–154. [148] M. Kaur, V. Kaur, A.K. Malik, N. Verma, B. Singha, A.L.J. Rao, Development of a derivative spectrophotometric method for the determination of fungicide zinc ethylenebisdithiocarbamate using sodium molybdate, J. Brazil. Chem. Soc. 20 (2009) 993–998. [149] A.S. Nateri, E. Ekrami, Quantitative analysis of bicomponent dye solutions by derivative spectrophotometry, Pigm. Resin Technol. 38 (2009) 43–48.

[150] B. Gözmen, M. Turabik, A. Hesenov, Photocatalytic degradation of basic red 46 and basic yellow 28 in single and binary mixture by UV/TiO2/periodate system, J. Hazard. Mater. 164 (2009) 1487–1495. [151] V.C. Almeida, A.M.M. Vargas, J.C. Garcia, E. Lenzi, C.C. Oliveira, J. Nozaki, Simultaneous determination of the textile dyes in industrial effluents by first-order derivative spectrophotometry, Anal. Sci. 25 (2009) 487–492. [152] J.F. Gao, Q. Zhang, K. Su, J.H. Wang, Competitive biosorption of yellow 2G and reactive brilliant red K-2G onto inactive aerobic granules: simultaneous determination of two dyes by first-order derivative spectrophotometry and isotherm studies, Bioresour. Technol. 101 (2010) 5793–5801. [153] A. Shams-Nateri, Prediction of dye concentrations in a three-component dye mixture solution by a PCA-derivative spectrophotometry technique, Color. Res. Appl. 35 (2010) 29–33. [154] A. Özer, M. Turabik, Competitive biosorption of acid dyes from binary solutions onto enteromorpha prolifera: application of the first order derivative spectrophotometric analysis method, Sep. Sci. Technol. 45 (2010) 380–393. [155] K. Shayesteh, J. Moghaddas, M. Haghighi, H. Eskandari, Development of a monitoring method for oxidative coupling reaction of 2-naphthol in solid state, Asian J. Chem. 22 (2010) 2106–2116. [156] F. Liu, Z.W. Wang, M.Y. Gu, Z.N. Wang, Entrapment efficiency of all-trans retinoic acid in surfactant vesicles, J. Dispersion Sci. Technol. 30 (2009) 1442–1448. [157] T. Hammady, A. El-Gindy, E. Lejmi, R.S. Dhanikula, P. Moreau, P. Hildgen, Characteristics and properties of nanospheres co-loaded with lipophilic and hydrophilic drug models, Int. J. Pharm. 369 (2009) 185–195. [158] J.M. Cano Pavón, A. García de Torres, C. Bosch Ojeda, F. Sánchez Rojas, E.I. Vereda Alonso, Derivative techniques in molecular absorption, fluorimetry and liquid chromatography as tool for green analytical chemistry, Handbook of Green Analytical Chemistry, first edition, John Wiley & Sons, 2012, pp. 245−259–245−259.