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Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application
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Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application Y. EL Bouabi a, A. Farahi a,b, M. Achak c, M. Zeroual a, K. Hnini a, S. El Houssame a, M. Bakasse d, A. Bouzidi a, M.A. El Mhammedi a,∗ a
Univ Hassan 1, Laboratoire de Chimie et Modélisation Mathématique, 25 000 Khouribga, Morocco Université Ibn Zohr, Faculté de Sciences, BP 8106 Cité Dakhla, Agadir, Morocco Ecole Nationale des Sciences Appliquées, Laboratoire des Sciences de l’Ingénieur Pour l’Energie, Université Chouaib Doukkali, El Jadida, Morocco d Laboratoire de Chimie Organique Bioorganique et Environnement, Faculté de Sciences, Université Chouaib Doukkali, Morocco b c
a r t i c l e
i n f o
Article history: Received 13 December 2015 Revised 26 May 2016 Accepted 15 June 2016 Available online xxx Keywords: Fluoroapatite Square wave voltammetry Paracetamol Water Tablets Urine
a b s t r a c t A carbon paste electrode modified with fluoroapatite (FAP–CPE) was examined to catalyze the electrochemical reduction of paracetamol (PCT). The FAP–CPE has demonstrated an efficient performance toward PCT reduction compared to that obtained using unmodified carbon electrode. The electrochemical behavior of PCT has been investigated and the optimum experimental conditions were achieved. Moreover, a good linear relationship was achievable over the concentration range from 4.0 × 10−8 mol/L to 1.0 × 10−3 mol/L using square wave voltammetry (SWV). The detection limit (S/N = 3) was also calculated and a low value of 1.25 × 10−8 mol/L was obtained with 210 s of accumulation time. The effect of coexisting of interferent compounds such as ascorbic acid (AA), citric acid (CA) and a binary mixture with dopamine (DA) was also investigated. The proposed method was successfully applied to PCT determination in natural waters, tablets and urine samples with the results agreeing with independently verified HPLC. © 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
1. Introduction Drug analysis plays a major role in the quality control of drug formulations which has great health risks. A simple, sensitive and accurate method to determine the active ingredients in drugs seems essential [1]. Paracetamol (acetaminophen) is one of the important drug having antipyretic and analgesic properties most frequently prescribed throughout the world. It has been proved to be extremely efficient for the mild pain relief, muscular aches, neuralgia, migraine headache, rheumatic pain, fever and osteoarthritis [2]. In general, PCT seems to be safe and appears to have no toxic effects on human’s health when taken in normal therapeutic doses [3]. However, taking high doses of PCT may cause adverse effects in the body, although in proper doses it does not display any side effects. Nowadays, PCT is widely used for its remarkable therapeutic characteristics thus precise determination and control of its quality is vital [4].
∗
Corresponding author. Tel.: +212 68858296; fax: +212 23485201. E-mail address: [email protected], [email protected] (M.A. El Mhammedi).
The review of literature for the assessment of PCT either individual or in combined dosage form reveals that a number of methods have been reported based on various analytical techniques. Those established methods include capillary electrophoresis (CE) [5], high performance liquid chromatography (HPLC) [6–8], HPLCtandem mass spectrometry [9], TLC [10], UV-spectrophotometry [11,12], titrimetry [13], spectrofluorometry [14], colorimetry [15], Fourier transform infrared spectrometry [16] and thermogravimetric analysis (TGA) [17]. However, although the analysis of PCT has been extensively studied, to our knowledge few works based on electrochemical methods using modified electrodes have been developed [18–20]. In addition, the electrochemical methods are very simple, highly sensitive and low apparatus cost than other traditional methods [21]. It is noteworthy, that the modified electrodes show a high sensitivity and selectivity toward the determination of PCT [22,23] than the unmodified ones [24]. The low biodegradability of PCT motivates us to develop the redox methods favoring its electrochemical activity. Indeed, the electrocatalytic reduction or oxidation can be advantageously applied to the extensive treatment of real matrices to detect and eliminate PCT. Consequently, a suitable catalyst is of great interest in real applications and it can be used to accelerate the reduction of PCT with a significant increase of the reduction currents and a shift of potentials towards less negative values.
http://dx.doi.org/10.1016/j.jtice.2016.06.013 1876-1070/© 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 1. (A) CVs of 1.0 × 10−4 mol/L PCT on the (a) CPE and (b) FAP−CPE at scan rate of 50 mV/s in 0.1 mol/L PBS (pH 7.0). (B) Square wave voltammograms of 1.0 × 10−4 mol/L PCT in 0.1 mol/L PBS at (a) CPE and (b) FAP−CPE (FAP/CP of (6/4: w/w).
Continuing with our interest in the use of fluoroapatite (FAP) as a carbon paste modified electrodes having sensing probes toward the oxidation or reduction of various electroactive species [25,26]. Among the different inorganic solids, FAP has advantages because it is cheap, readily available, stable in water, non-toxic, not a pollutant and, in particular, the fluorapatite is reputed unanimously for their weak solubility [27], herein we report an efficient and pertinent method for the electroreduction of PCT using square wave voltammetry. This methodology has been successfully applied to construct an enhanced sensing platform for the electrochemical detection of PCT in natural water samples, commercial tablets and human urines without any sample pre-purification steps. 2. Experimental 2.1. Reagents All chemicals used were of analytical grade or of the highest purity available. FAP [28], sodium hydroxide, sodium phosphate dibasic, monosodium phosphate and chloridric acid were purchased from commercial sources and used as received. Paracetamol (Malinkroute, 99.99%) was dissolved in phosphate buffer solution (0.1 mol/L) to prepare stock solutions of 1.0 × 10−3 mol/L. Then the working standard solutions were prepared by successive dilution of the stock solutions by sodium sulfate. Carbon paste was supplied from Carbone, Lorraine, ref 9900, France. All the reagents used were of analytical grade. Distilled water (DW) was used throughout the preparation of the solutions. 2.2. Instrument Electrochemical measurements were carried out by using an eDAQ e-corder/potentiostat EA163 controlled by eDAQ EChem data acquisition software and equipped with three electrode system mounted on cell. Working electrode was FAP-modified carbon paste electrode, the counter electrode was a platinum plate and Ag/AgCl/Cl− (3 mol/L) served as reference. The pH-meter (Radiometer, sensIONTM , PH31, Spain) was used for adjusting pH values. The electrochemical impedance measurements were done via an electrochemical impedance analyzer potentiostat (model PGZ 100, Eco Chemie B.V., Utrecht, The Netherlands) using a computer controlled by voltalab master 4 software logiciel.
2.3. Preparation of the chemically modified electrode The modified carbon-paste electrode was prepared by mixing the graphite powder with the fluoroapatite to give a ratio FAP/CP of (6/4 : w/w). Portions of the resulting composite material were then packed into a home built electrode assembly consisting of the cavity (geometric area 0.1256 cm2 ) of PTFE cylindrical tube electrode of a plastic pipette tip. Electrical contact was established with a bar of carbon. 2.4. Electrochemical measurements A glass cell was washed with 10% hydrochloric acid then rinsed with DBW. Two-step procedures were followed for the analytical determination of PCT in aqueous samples. At open circuit, the working electrode was first immersed in 0.1 mol/L phosphate buffer solution (PBS) containing PCT. Where the accumulation of PCT was achieved chemically, the square wave experiments were performed in PBS electrolyte solutions at FAP–CPE. The potential range was performed from 0.0 mV to 500 mV with a frequency of 30 Hz, pulse height of 40 mV and modulation amplitude 5 mV at scan rate 150 mV/s. The cyclic voltammogram was recorded between −0.4 and −1.0 V. EIS was performed between 100 kHz and 100 mHz at AC amplitude of 10 mV. All measurements were performed at room temperature. 2.5. HPLC analysis of paracetamol The chromatographic separation was applied using a mobile phase of water and methanol (20/80), through a Nucleosil 1005 C18 (250 × 4.6 mm I.D. 5 μm) column (Macherey-Nagel, Germany), with an injection volume of 10 μl, and a flow rate set to 1.0 mL/min. The detector responses were measured in terms of peak area, using the Borwin chromatographic software for storage, and data mining process. 3. Results and discussion 3.1. Electrocatalytic behaviors of PCT at FAP−CPE 3.1.1. Comparisons between CPE and FAP−CPE The electrochemical response of 1.0 × 10−4 mol/L PCT in 0.1 mol/L phosphate buffer (pH 7) at the working electrodes have been studied by using cyclic voltammetry (Fig. 1A). On the unmodified CPE (Fig. 1Aa), PCT shows a quasi-reversible redox. In the case
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 2. CVs of 1.0 × 10−4 mol/L PCT on FAP−CPE at different scan rates (1, 5, 10, 50, 100, 160, 200, 250 and 320 mV/s) in 0.1 mol/L PBS (pH 7.0). Inset, the plot of the peak current vs. scan rate.
of FAP−CPE, a pair of well-defined and reversible redox peaks corresponding to the electrochemical reaction of PCT was obtained, with Epa = 446 mV and Epc = 330 mV. It can be seen that the reduction over potential of PCT becomes higher than that on CPE with a positive shifting of 314 mV. An Epa shifted toward negative potentials in the presence of the fluoroapatite (Fig. 1Bb) was shown. The results demonstrated that the electrochemical reactivity of PCT is remarkably improved on the FAP−CPE. Owing to its high adsorptivity and good biocompatibility, FAP particles effectively modify the surface chemistry of carbon, which provides an efficient interface and microenvironment for the electrochemical reaction of PCT. Results confirm that the FAP can catalyze paracetamol oxidation, this was possible thanks to their structure, the presence of Brønsted acid sites and Lewis and their ability to make exchanges ion. In the square wave voltammetric, the oxidation peak currents of paracetamol on the FAP–CPE were about 80 fold higher than that of the unmodified electrodes (Fig. 1B). 3.1.2. Effect of scan rate The scan rate effect on the anodic and cathodic peak current of PCT on the FAP−CPE was investigated. As shown in Fig. 2, the anodic and cathodic peak currents increase as the scan rate grows from 5 to 250 mV/s. The linear relationship between the peak current and square root of scan rate can be expressed by the linear regression equations as: Ipa/μA = 8.16(v)1/2 −12.62 (R² = 0.982) and Ipc/μA = −2.39(v)1/2 −4.30 (R² = 0.988), respectively. According to the literature, the results indicate that the electrochemical reaction of PCT on the FAP−CPE is a surface-controlled process [29,30]. In addition, Epc is shifted to positive potentials, while Epa is neg-
atively shifted. This can be due to changes in the electroactivity and kinetic effect of FAP−CPE surface on the reduction of PCT especially at scan rates lower than 5 mV/s. In other words, at scan rates lower than 5 mV/s the time window for the PCT oxidation becomes very narrow, avoiding the facile electron transfer between substrate and catalytic sites. At high scan rates ranging from 1 to 320 mV/s, plotting the Epa and Epc vs. lnv produces a straight line with the linear regression equations as: Epa = 0.032 ln(v) + 0.276 (R² = 0.958) and Epc = −0.027ln(v) + 0.475 (R² = 0.996), respectively. According to Laviron’s equation [31], the slops of the lines are equal to RT/α nF and −RT/α nF, respectively. Therefore, the electron transfer coefficient (α ) and the electron transfer number (n) are calculated to be 0.54 and 2, respectively. The adsorbed amount of PCT on the surface of FAP−CPE was further calculated by the following equation: ip = n2 F2 A Гv/4RT [31]. Based on the relationship of ip with v, the value of the surface concentration of the PCT (Г) was obtained with the results as 4.54 × 10−8 mol/cm2 . This high surface concentration can be attributed to the FAP modifier. 3.1.3. Effect of pH Fig. 3 represents CVs of the modified electrode in 1.0 × 10−4 mol/L PCT at various pH values. A decrease in pH of the solution from 12.0 to 2.0 led to a positive shift in both reduction and oxidation peak potentials. So the peak potentials seem to be affected by the concentration of H+ , suggesting the presence of protonation step in the electrochemical mechanism as indicated in Schema 1. However, there was no considerable decrease in the peak currents. These results indicated that the slope was 45.0 ± 0.65 mV/pH over a pH range of 2.0 to 12.0. This
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 3. CVs of FAP–CPE at different pH values: 2.0–12.0; 1.0 × 10−4 mol/L in 0.1 mol/L PBS; Plot of Epc vs. pH value.
O
O HN
C
N
CH3
C
CH3
- 2H+ - 2e-
OH
O Schema 1. Proposed mechanism of PCT reduction.
used to evaluate the electrocatalytic effect of the fluoroapatite. Fig. 4 represents the current-time profiles obtained by setting the working electrode potential. As seen, the behavior is typical of that expected for a mediated reduction. We found that cathodic current of the PCT on FAP−CPE is still higher than that measured on the unmodified carbon paste electrode, indicating that electrode FAP−CPE has high catalytic ability to reduce PCT. This confirms the results previously obtained by cyclic voltammetry. The performance of PCT reduction on the FAP−CPE reached 50% compared to CPE. The results obtained by chronoamperometry, show that electrode FAP−CPE can effectively catalyze the reduction of PCT. 3.3. Electrochemical impedance spectroscopy studies
value was smaller than the ideal Nernst’s value of 59.2 mV/pH for a two electron and two proton process [32]. According to the literature, we can predict that the mechanism depicted in Schema 1, seemed to be proposed for the reduction of PCT [33–36]. This behavior is due to the contribution of H+ ions and the structural changes in –OH– and –NHCOCH3 groups of PCT which get involved in the reduction process of paracetamol [37,38]. Therefore, pH 7.0 was selected as the optimum pH for the electrochemical determination of PCT, which is close to the physiological conditions.
Fig. 5 shows Nyquist plots of 1.0 × 10−4 mol/L in the 0.1 mol/L PBS at these electrodes within the frequency range of 100 kHz to 100 mHz at the formal potential of the redox probe. The almost straight line plots obtained implies the low charge transfer resistance of the redox probe [39,40]. At high frequencies, CPE (curve a) experiences a sharp increase of Zim and behaves closer to an ideal capacitor [41]. The presence of a small and depressed semicircle in curve (b) at lower frequencies could be due to the charge-transfer resistance (Rct) of the electrodes. The FAP–CPE has a higher Rct which implies that the interfacial resistance has increased. This result explains the fixation of the paracetamol onto electrode surface.
3.2. Chronoamperometry studies of PCT at FAP−CPE
3.4. Electroanalytical studies of PCT at FAP−CPE
To confirm the results obtained by cyclic voltammetry, the chronoamperometry as another electrochemical technique was
In order to quantify PCT, experimental conditions has been optimized using the relationships between peak current (IP) and the
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 4. Chronoamperograms obtained of PCT at different reduction potential, 1.0 × 10−4 mol/L in 0.1 mol/L PBS.
Fig. 5. Impedance spectra at 0 V (a) CPE−PCT and (b) FAP−CPE−PCT.
chemical and electrochemical parameters. All these parameters exert an intense effect on the peak current. An increasing of the pulse height from 10 to 70 mV led to the increase of peak currents of PCT. However, after 40 mV, it caused peak broadening. Therefore, a value of 40 mV was chosen as optimal pulse height for further studies. The influence on the frequency of the current intensity of PCT was evaluated in the range of 5 to 40 Hz (Fig. 6). The signal increases with the increase of the frequency. Thus, in further experiments a value of 30 Hz, corresponds to 0.033 s of duration for each step, was employed to ensure the maximum diffusion of the electro-active species to electrode surfaces. We can assume that
the redox process involves the adsorption as the rate-determining step [42]. This behavior is typical of the responses obtained at electrodes, where the electroactive species interact with working electrode, in the adsorption process, before the redox reaction occurs. The results confirm those obtained by varying the scan rate in cyclic volammetry. We have also investigated the amplitude influence in the range from 1 to 15 mV. The results obtained demonstrated that a height of PCT peak increased linearly as a consequence of the increase in amplitude values up to 5 mV. In agreement with the high peak current values, good shapes of the signal and better signal to noise ratio were obtained, the selected optimal values were 30 Hz, 40 mV and 5 mV for frequency, modulation amplitude and pulse height respectively. The effect of pH on the determination of PCT in PBS solution at the FAP–CPE was carefully investigated in the pH range of 3.0– 8.0. The anodic peak current of PCT increases with increasing pH values until the pH reaches 6.8–7.0, the anodic peak current then decreases with further increases in the pH. The maximum anodic peak current appeared at pH 7.0. Therefore, PBS with a pH of 7.0 was selected for all subsequent electrochemical PCT analyses. Accumulation time is an important parameter for SWV technique and has a non-negligible influence on the sensitivity of determination of PCT (Fig. 6). It is clear that the anodic peak intensity increased with the increase of the preconcentration times in the range from 10 s to 600 s, the anodic peak current decreased significantly around 210 s after saturation of electrode surfaces. Taking account of sensitivity and efficiency, accumulation time was 210 s in the following experiments. The square wave voltammograms (Fig. 6) demonstrated that the increase of the concentration of fluoroapatite as modifier (from 10 to 80% by weight of carbon paste), affects the electrochemical behaviors of PCT at the carbon paste electrode. The peak currents
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 6. Influence of the experimental variables (pulse height, amplitude, frequency, pH, time preconcentration and Percentage FAP/CP) involved in the SWV method and response to PCT 1.0 × 10−4 mol/L in 0.1 mol/L PBS at the FAP−CPE.
of PCT increase with the increase of the modifier amount. Moreover, the intensity of peak decreases if the concentration of modifier is higher than 60% of FAP loading by weight (w/w). This result is probably due to the decrease in the modified electrode conductivity. In the course of the study, a modifier concentration of about 60% of the ratio FAP/CP is used.
3.5. Linear range and detection limit The calibration curve for the SWV peak current for PCT oxidation vs. PCT concentration shows excellent linearity over a wide concentration range from 1.0 × 10−3 to 4.0 × 10−8 mol/L (Fig. 7). It can be seen that the calibration plots of peak current vs. concentration of PCT show two linear dynamic ranges from 1.0 × 10−3 –4.0 × 10−5 mol/L and 2.0 × 10−5 –4.0 × 10−8 mol/L (Fig. 7). The linear regression equations for these two regions are ipa(μA) = 0.037 [PCT] (mol/L) + 124.1 (R² = 0.977) and ipa(μA)=3.238[PCT] (mol/L) + 25.73 (R² = 0.990). The standard deviation of the mean current (sb) measured at the oxidation potential of paracetamol for 10 voltammograms of the blank solution in pure electrolytes was used [43] in the determination of the quantification limit (LOQ, 10 s) and the detection limit (LOD, 3 s) together with the slope of the straight line of the analytical curves. The limit of detection (DL) and limit of quantification (QL) are calculated to be respectively 1.25 × 10−8 mol/L and 4.16 × 10−8 mol/L. The precision (n = 8) assessed as relative standard deviation (R.S.D.) were 1.24% for 1.0 × 10−6 mol/L and 1.07% for 4.0 × 10−6 mol/L, respectively. The electrochemical behavior of FAP−CPE for PCT was contrasted with some of the previously reported electrodes (Table 1). It is obvious that PCT at FAP−CPE showed a low relative standard deviation, broad linearity range, and a low detection limit.
The FAP−CPE electrode here could maintain its activity as a sensor for parectamol during 4 months; the response was 97.15% of its initial value which shows long-term stability and very good sensitivity for the analysis of paracetamol. 3.6. Effect of interferents In order to evaluate the selectivity of the prepared sensor, the effect of various possible interferents on the determination of PCT was examined, and the results were summarized in Table 2. It was observed that Na+ , Mg2+ , Ca2+ , Cu2+ , Pb2+ , Cd2+ , K+ , Ni2+ , Co3+ , Zn2+ , Al3+ , Fe3+ , Fe2+ , V5+ , Cr3+ , NO3 − , showed no obvious interference for the determination of 1.0 × 10−5 mol/L PCT even when present 100 times in excess, with deviations below 4%. However, Ag+ was found to affect the detection of PCT. It was found that 100-fold of Ag+ interfered with the determination of 1.0 × 10−5 mol/L PCT (peak current change 5.83%). The influences of the presence of organic elements on the PCT signals were also tested. At the same concentration, ascorbic acid, citric acid, ibuprofen and dopamine had no apparent effects on the current response of PCT (˂2%). Electrochemically active ascorbic acid (vitamin C) is often combined with PCT based drugs. No significant interference effect was observed in the developed SWV method up to 10 fold concentration of ascorbic acid (Ep ≈ −200 mV) in comparison with concentration of PCT (Ep ≈ +400 mV). As in the case of ascorbic acid, no significant interference effect of dopamine (Ep ≈ +200 mV) was observed under the same conditions. Both these results indicate the possibility of eventual determination of PCT simultaneously with ascorbic acid or dopamine. 3.7. Practical application In order to evaluate the performance of FAP−CPE by practical analytical applications, the determination of PCT was carried out in
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 7. SWV curves of different concentrations of PCT in 0.1 mol/L PBS (pH 7) at FAP−CPE: 1.0 × 10−3 – 4.0 × 10−5 mol/L and 2.0 × 10−5 −4.0 × 10−8 mol/L.
Table 1 Comparison of the electrochemical behavior of PCT at FAP−CPE with some of the previously reported electrodes. Methods Cu-PTTCA/GCE VCPTE Nafion/GCE GCE CILE C60/GCE PANI-MWCNTs/GCE C–Ni/GCE PAY/nano-TiO2 /GCE FAP-CPE
Linear range (μmol/L) 20–50 0 0 0.120–5800 50–500 2–1580 1.0–20 0 0 50–1500 1–100 2–230 12–120 10 0 0–4.0 0 and 200–0.04
DL (mol/L) −6
5.0 × 10 88.0 × 10−6 17.0 × 10−6 19.0 × 10−6 0.3 × 10−6 0.5 × 10−4 2.5 × 10−7 6.0 × 10−7 2.0 × 10−6 1.25 × 10–8
DSR (%)
Refs
– – – – – – 3.9 1.1 – 1.07
[44] [45] [46] [47] [48] [49] [50] [51] [52] Present work
Cu-PTTCA/GCE: Cu-poly terthiophene carboxylic acid modified glassy carbon electrode. VCPTE: Vaseline carbon paste tissue electrode. Nafion/GCE: Nafion modified glassy carbon electrode. GCE: Glassy carbon electrode. CILE: carbon ionic liquid electrode. PAYnano-TiO2 /GCE: poly(acid yellow 9)/nano-TiO2 modified glassy carbon electrode. C60/GCE: C60-modified glassy carbon electrode. PANI-MWCNTs/GCE: A polyaniline–multi-walled carbon nanotubes (PANI–MWCNTs) composite modified electrode. C–Ni/GCE: A novel type of carbon-coated nickel magnetic nanoparticles modified glass carbon electrodes.
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Y. EL Bouabi et al. / Journal of the Taiwan Institute of Chemical Engineers 000 (2016) 1–10 Table 2 Influence of coexisting substances on the determination of 1.0 × 10−4 mol/L PCT (n = 3). Coexisting substance +
Na Mg2+ Ca2+ Cu2+ Pb2+ Cd2+ K+1 Ni2+ CO2+ Zn2+ Ag+
Concentration (mmol/L)
Change of peak current (%)
3+
−1.27 −1.65 −1.89 −1.20 1.48 −1.47 0.85 0.55 −0.28 −1.42 −5.83
1 1 1 1 1 1 1 1 1 1 1
Coexisting substance Al Fe3+ Fe2+ V5+ Cr3+ NO3 − Ibuprofen Ascorbic acid Citric acid Dopamine
Concentration (mmol/L)
Change of peak current (%)
1 1 1 1 1 1 0.1 0.1 0.1 0.1
0.45 0.56 0.67 1.52 0.22 −1.27 −0.40 −1.72 −1.5 −1.06
Fig. 8. Curves calibration of the determination of PCT in: (a) seawater (b) river water. Table 3 Determination of PCT in water samples and human urines. (FAP-CPE) Samples
PCT Added (×10
River water River water Sea water Sea water Human urines Human urines Human urines
2 4 2 4 2 4 6
−5
mol/L)
PCT found (×10
(HPLC) −5
1.94 3.96 1.92 3.95 1.90 3.92 5.91
mol/L)
Recovery (%)
PCT found (×10−5 mol/L)
Recovery (%)
97.00 ± 9.45 99.00 ± 5.74 96.00 ± 11.31 98.75 ± 6.41 95.00 ± 12.58 98.00 ± 8.08 98.50 ± 7.01
1.96 3.99 1.98 3.97 1.95 3.94 5.99
98.00 99.75 99.00 99.25 97.50 98.50 99.83
All samples were analyzed using standard addition method (n = 3). √ ∗ Extended DPV-recovery (R) = ± (R0 (1 − R0 )/n (n = 3), where R0 is the percentage recovery, t is a distribution value chosen for the desired confidence level. Theoretical values at 95% confidence limits: t = 2.78.
real samples (river water, seawater, commercial tablets and human urines). (i) River water and seawater The experiments were carried out by adding a known amount of PCT to the support electrolyte followed by standard additions from the PCT stock solution and plotting the resulting analytical curve. The support electrolytes were prepared by addition of 0.1 mol/L of PBS to a fresh water samples. The plot of peak currents against PCT concentration was linear (Fig. 8). The results of the determination of PCT using calibration curves are given in Table 3. No
interference of the matrix components was observed even without any sample pretreatment. No signal for PCT was observed when the water samples were analyzed, which may be attributed to that no PCT is in water samples or the concentration of PCT is lower than the detection limit. (ii) Determination of PCT in urine samples FAP–CPE is investigated for the measurement of PCT in three human urine samples. The percentage of recovery of the spiked sample is in the range between 98.00 and 98.50. The results obtained by this method agreed with those by the HPLC. The result
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Table 4 Determination results of PCT in tablets by FAP−CPE (n = 5). (FAP–CPE)
(HPLC)
Sample
Label (mg/tablet)
PCT found (mg/tablet)
RSD (%)
Recovery (%)
PCT found (mg/tablet)
Recovery (%)
Doliprane Panadol
10 0 0 500
980 489
1.85 1.74
98.00 97.80
985 491
98.50 98.20
in Table 3 was mean value of replicating measurement of three times. Model human urine samples were used to demonstrate that matrix components do not interfere with PCT determination. The results show that the modified electrode is suitable for the determination of PCT in biological fluids (iii) Determination of PCT in formulation tablets The developed method was applied to the analysis of two different commercial tablets. The tablets were weighed, ground into powder, and then dissolved in 0.1 PBS mol/L adequately. All the sample solutions were transferred to 25 mL flask and diluted with PBS (pH 7.0). The mean percentage recoveries of added PCT were found to be 97.80% and 98.00% using the proposed method and HPLC, respectively (Table 4). There were no significant differences between the recoveries calculated at the 95 % confidence level and within an acceptable range error of 5%. The excellent average recoveries of formulation tablets samples suggest that the FAP−CPE developed in this work has practical significance and is able to determine PCT in formulation tablets. 4. Conclusion A highly advanced and sensitive FAP−CPE toward PCT reduction has been disclosed. The performances of FAP−CPE were significantly better than those of CPE because it exhibited a remarkably enhanced electrocatalytical activity toward the sensing of PCT. The influence of the experimental variables which involved in the SWV determination of PCT was investigated. Analytical results show that the proposed modified electrode was able to detect 1.25 × 10−8 mol/L of PCT with good sensitivity and repeatability. Results of voltammetric determination of PCT in real samples were in good agreement with those of HPLC methods proving that FAP−CPE offers a useful and reliable method for the quantification of PCT in real samples. Acknowledgments The authors wish to express their appreciation to the Hassan 1er University. This study could not have been conducted without their financial supports. References [1] Sun D, Zhang H. Electrochemical determination of acetaminophen using a glassy carbon electrode coated with a single-wall carbon nanotube-dicetyl phosphate film. Microchim Acta 2007;158:131–6. [2] Yin H, Shang K, Meng X, Ai S. Voltammetric sensing of paracetamol, dopamine and 4-aminophenol at a glassy carbon electrode coated with gold nanoparticles and an organophilliclayered double hydroxide. Microchim Acta 2011;175:39–46. [3] Tsierkezos NG, Othman SH, Ritter U. Nitrogen-doped multi-walled carbon nanotubes for PCT sensing. Ionics 2013;19:1897–905. [4] Lourenção BC, Medeiros RA, Rocha-Filho RC, Mazo LH, Fatibello-Filho O. Simultaneous voltammetric determination of PCT and caffeine in pharmaceutical formulations using a boron-doped diamond electrode. Talanta 2009;78:748–52. [5] Sultan MA, Maher HM, Alzoman NZ, Alshehri MM, Rizk MS, Elshahed MS, et al. Capillary electrophoretic determination of antimigraine formulations containing caffeine, ergotamine, PCT and domperidone or metoclopramide. Chromatogr Sci Ser 2013;51:502–10.
[6] Abdelaleem EA, Abdelwahab NS. Validated stability indicating RP-HPLC method for determination of PCT, methocarbamol and their related substances. Anal Methods 2013;5:541–5. [7] Wilson JM, Slattery JT, Forte AJ, Nelson SD. Analysis of acetaminophen metabolites in urine by high performance liquid chromatography with UV and amperometric detection. J Chromatogr B Biomed Sci Appl 1982;227:453–62. [8] Ravisankar S, Vasudevan M, Gandhimathi M, Suresh B. Reversed-phase HPLC method for the estimation of acetaminophen, ibuprofen and chlorzoxazone in formulations. Talanta 1998;46:1577–81. [9] Modick H, Schütze A, Pälmke C, Weiss T, Brüning T, Koch HM. Rapid determination of N-acetyl-4-aminophenol (paracetamol) in urine by tandem mass spectrometry coupled with on-line clean-up by two dimensional turbulent flow/reversed phase liquid chromatography. J Chromatogr B Analyt Technol Biomed Life Sci 2013;925:33–9. [10] Roy J, Saha P, Sultana S, Kenyon AS. Rapid screening of marketed paracetamol tablets: use of thin-layer chromatography and a semi quantitative spot test. Bull World Health Organ 1997;75:19–22. [11] Abirami G, Vetrichelvan T. simultaneous determination of tolperisone and paracetamol in pure an fixed dose combination by UV-Spectrophotometry. Int J Pharm Pharm Sci 2013;5:488–92. [12] Canada MJA, Reguera MIP, Medina AR, De Cordova MLF, Diaz AM. Fast determination of paracetamol by using a very simple photometric flow-through sensing device. J Pharm Biomed Anal 20 0 0;22:59–66. [13] Srivastava MK, Ahmed S, Singh D, Shukla IC. Titrimetric determination of dipyrone and paracetamol with potassium hexacyanoferrate (III) in an acidic medium. Analyst 1985;110:735–7. [14] Vilchez JL, Blanc R, Avidad R, Navalon A. Spectrofluorimetric determination of paracetamol in pharmaceuticals and biological fluids. J Pharm Biomed Anal 1995;13:1119–25. [15] Knochen M, Giglio J, Reis BF. Flow-injection spectrophotometric determination of paracetamol in tablets and oral solutions. J Pharm Biomed Anal 2003;33:191–7. [16] Ramos ML, Tyson JF, Curran DJ. Determination of acetaminophen by flow injection with on-line chemical derivatization: investigations using visible and FTIR spectrophotometry. Anal Chim Acta 1998;364:107–16. [17] Khanmohammadi M, Soleimani M, Morovvata F, Garmarudi AB, Khalafbeigi M, Ghasemi K. Simultaneous determination of paracetamol and codeine phosphate in tablets by TGA and chemometrics. Thermochim Acta 2012;530:128–32. [18] Pedrosa VA, Lowinsohn D, Bertotti M. FIA determination of paracetamol in pharmaceutical drugs by using gold electrodes modified with a 3-mercaptopropionic acid monolayer. Electroanalysis 2006;18:931–4. [19] Radovan C, Cofan C, Cinghita D. Simultaneous determination of acetaminophen and ascorbic acid at an unmodified boron-doped diamond electrode by differential pulse voltammetry in buffered media. Electroanalysis 2008;20:1346–53. [20] Li M, Jing L. Electrochemical behavior of acetaminophen and its detection on the PANI–MWCNTs composite modified electrode. Electrochim Acta 2007;52:3250–7. [21] Lau OW, Luk SF, Cheung YM. Simultaneous determination of ascorbic acid, caffeine and paracetamol in drug formulations by differential-pulse voltammetry using a glassy carbon electrode. Analyst 1989;114:1047–51. [22] Xu ZM, Yue Q, Zhuang ZJ, Xiao D. Flow injection amperometric determination of acetaminophen at a gold nanoparticle modified carbon paste electrode. Microchim Acta 2009;164:387–93. [23] Teixeira MFS, Marcolino LH, Fatibello O, Moraes FC, Nunes RS. Determination of analgesics (dipyrone and acetaminophen) in pharmaceutical preparations by cyclic voltammetry at a copper(II) hexacyanoferrate(III) modified carbon paste electrode. Curr Anal Chem 2009;5:303–10. [24] Skeika T, De Faria MF, Nagata N, Pessoa CA. Simultaneous voltammetric determination of dypirone and paracetamol with carbon paste electrode and multivariate calibration methodology. J Braz Chem Soc 2008;19:762–8. [25] Hidalgo-Carrillo J, Sebti J, Aramendía MA, Marinas A, Marinas JM, Sebti S, et al. A study on the potential application of natural phosphate in photocatalytic processes. J Colloid Interf Sci 2010;344:475–81. [26] Sebti S, Zahouily M, Lazrek HB, Mayoral JA, Macquarrie DJ. Phosphates: new generation of liquid-phase heterogeneous catalysts in organic chemistry. Curr Org Chem 2008;12:203–32. [27] Vieillard P, Tardy Y, Nriagu JO, Moore PB. Phosphate minerals. New York: Springer-Verlag; 1984. [28] El Mhammedi MA, Bakasse M, Chtaini A. Investigation of square wave voltammetric detection of diquat at carbon paste electrode impregnated with Ca10 (PO4 )6F2 : application in natural water samples. Mater Chem Phys 2008;109:519–25.
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[m5G;June 28, 2016;19:8]
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[29] Dalmasso PR, Pedano ML, Rivas GA. Electrochemical determination of ascorbic acid and paracetamol in pharmaceutical formulations using a glassy carbon electrode modified with multi-wall carbon nanotubes dispersed in polyhistidine. Sens Actuators: B Chem 2012;173:732–6. [30] Lu TL, Tsai YC. Sensitive electrochemical determination of acetaminophen in pharmaceutical formulations at multiwalled carbon nanotube-alumina– coated silica nanocomposite modified electrode. Sens Actuators: B Chem 2011;153:439–44. [31] Laviron E. General expression of the linear potential sweep voltammogram in the case of diffusion less electrochemical systems. J Electroanal Chem 1979;101:19–28. [32] Rahimi P, Rafiee-Pour H, Ghourchian H, Norouzi P, Ganjali MR. Ionic-liquid/ NH2-MWCNTs as a highly sensitive nano-composite for catalase direct electrochemistry. Biosens Bioelectron 2010;25:1301–6. [33] Ghorbani-Bidkorbeh F, Shahrokhian S, Mohammadi A, Dinarvand R. Simultaneous voltammetric determination of tramadol and acetaminophen using carbon nanoparticles modified glassy carbon electrode. Electrochim Acta 2010;55:2752–9. [34] Zidan M, Tan W, Abdullah AH, Zainal Z, Goh JK. Electrocatalytic oxidation of paracetamol mediated by lithium doped microparticles Bi2 O3 /MWCNT modified electrode. Asian J Chem 2011;23:3029–32. [35] Li C, Zhan G, Yang Q, Lu J. Electrochemical Investigation of acetaminophen with a carbon nano-tube composite film electrode. Bull Korean Chem Soc 2006;27:1854–60. [36] Sotomayor M, Sigoli A, Lanza MRV, Tanaka AA, Kubota LT. Construction and application of an electrochemical sensor for paracetamol determination based on iron tetrapyridinoporphyrazine as a biomimetic catalyst of P450 enzyme. J Braz Chem Soc 2008;19:734–43. [37] Su WY, Cheng SH. Electrochemical oxidation and sensitive determination of acetaminophen in pharmaceuticals at poly(3,4-ethylenedioxythiophene)modified screen-printed electrodes. Electroanalysis 2010;22:707–14. [38] Manjunatha R, Nagaraju DH, Suresh GS, Melo JS, D’Souza SF, Venkatesha TV. Electrochemical detection of acetaminophen on the functionalized MWCNTs modified electrode using layer-by-layer technique. Electrochim Acta 2011;56:6619–27. [39] Luo J, Jiang S, Zhang H, Jiang J, Liu X. A novel non-enzymatic glucose sensor based on Cu nanoparticle modified graphene sheets electrode. Anal Chim Acta 2012;709:47–53.
[40] Fan H, Li Y, Wu D, Ma H, Mao K, Fan D, et al. Electrochemical bisphenol A sensor based on N-doped grapheme sheets. Anal Chim Acta 2012;711:24–8. [41] Tehrani RMA, Ab Ghani S. MWCNT-ruthenium oxide composite paste electrode as non-enzymatic glucose sensor. Biosens Bioelectron 2012;38:278–83. [42] Lovric M, Komorsky-Lovric S. Square-wave voltammetry of an adsorbed reactant. J Electroanal Chem 1988;248:239–53. [43] Mocak J, Bond AM, Mitchel S, Scollary GA. Statistical overview of standard (IUPAC and ACS) and new procedures for determining the limits of detection and quantification: application to voltammetric and stripping techniques. Pure Appl Chem 1997;69:297–328. [44] Boopathi M, Won MS, Shim YB. A sensor for acetaminophen in a blood medium using a Cu(II)-conducting polymer complex modified electrode. Anal Chim Acta 2004;512:191–7. [45] Fatibello-Filho O, Lupetti KO, Vieira IC. Chronamperometric determination of paracetamol using an avocado tissue (Persea Americana) biosensor. Talanta 2001;55:685–92. [46] Silva MLS, Garcia MBQ, Lima JLFC, Barrado E. Modified tubular electrode in a multi-commutated flow system: determination of acetaminophen in blood serum and pharmaceutical formulations. Anal Chim Acta 2006;573–574:383–90. [47] Tungkananuruk K, Tungkananuruk N, Burns DT. Cyclic voltammetric determination of acetaminophen in paracetamol tablets. KMITL Sci Technol J 2005;5:547–51. [48] ShangGuan X, Zhang H, Zheng J. Electrochemical behavior and differential pulse voltammetric determination of paracetamol at a carbon ionic liquid electrode. J Anal Chem 2008;391:1049–55. [49] Goyal RN, Singh SP. Voltammetric determination of paracetamol at C60-modified glassy carbon electrode. Electrochim Acta 20 06;51:30 08–12. [50] Mingqi L, Linhai J. Electrochemical behavior of acetaminophen and its detection on the PANI–MWCNTs composite modified electrode. Electrochim Acta 2007;52:3250–7. [51] Wang SF, Xie F, Hu RF. Carbon-coated nickel magnetic nanoparticles modified electrodes as a sensor for determination of acetaminophen. Sens Actuators: B Chem 2007;123:495–500. [52] Kumar SA, Tang CF, Chen SM. Electroanalytical determination of acetaminophen using nano-TiO2 /polymer coated electrode in the presence of dopamine. Talanta 20 08;76:997–10 05.
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Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application Y. EL Bouabi a, A. Farahi a,b, M. Achak c, M. Zeroual a, K. Hnini a, S. El Houssame a, M. Bakasse d, A. Bouzidi a, M.A. El Mhammedi a,∗ a
Univ Hassan 1, Laboratoire de Chimie et Modélisation Mathématique, 25 000 Khouribga, Morocco Université Ibn Zohr, Faculté de Sciences, BP 8106 Cité Dakhla, Agadir, Morocco Ecole Nationale des Sciences Appliquées, Laboratoire des Sciences de l’Ingénieur Pour l’Energie, Université Chouaib Doukkali, El Jadida, Morocco d Laboratoire de Chimie Organique Bioorganique et Environnement, Faculté de Sciences, Université Chouaib Doukkali, Morocco b c
a r t i c l e
i n f o
Article history: Received 13 December 2015 Revised 26 May 2016 Accepted 15 June 2016 Available online xxx Keywords: Fluoroapatite Square wave voltammetry Paracetamol Water Tablets Urine
a b s t r a c t A carbon paste electrode modified with fluoroapatite (FAP–CPE) was examined to catalyze the electrochemical reduction of paracetamol (PCT). The FAP–CPE has demonstrated an efficient performance toward PCT reduction compared to that obtained using unmodified carbon electrode. The electrochemical behavior of PCT has been investigated and the optimum experimental conditions were achieved. Moreover, a good linear relationship was achievable over the concentration range from 4.0 × 10−8 mol/L to 1.0 × 10−3 mol/L using square wave voltammetry (SWV). The detection limit (S/N = 3) was also calculated and a low value of 1.25 × 10−8 mol/L was obtained with 210 s of accumulation time. The effect of coexisting of interferent compounds such as ascorbic acid (AA), citric acid (CA) and a binary mixture with dopamine (DA) was also investigated. The proposed method was successfully applied to PCT determination in natural waters, tablets and urine samples with the results agreeing with independently verified HPLC. © 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
1. Introduction Drug analysis plays a major role in the quality control of drug formulations which has great health risks. A simple, sensitive and accurate method to determine the active ingredients in drugs seems essential [1]. Paracetamol (acetaminophen) is one of the important drug having antipyretic and analgesic properties most frequently prescribed throughout the world. It has been proved to be extremely efficient for the mild pain relief, muscular aches, neuralgia, migraine headache, rheumatic pain, fever and osteoarthritis [2]. In general, PCT seems to be safe and appears to have no toxic effects on human’s health when taken in normal therapeutic doses [3]. However, taking high doses of PCT may cause adverse effects in the body, although in proper doses it does not display any side effects. Nowadays, PCT is widely used for its remarkable therapeutic characteristics thus precise determination and control of its quality is vital [4].
∗
Corresponding author. Tel.: +212 68858296; fax: +212 23485201. E-mail address: [email protected], [email protected] (M.A. El Mhammedi).
The review of literature for the assessment of PCT either individual or in combined dosage form reveals that a number of methods have been reported based on various analytical techniques. Those established methods include capillary electrophoresis (CE) [5], high performance liquid chromatography (HPLC) [6–8], HPLCtandem mass spectrometry [9], TLC [10], UV-spectrophotometry [11,12], titrimetry [13], spectrofluorometry [14], colorimetry [15], Fourier transform infrared spectrometry [16] and thermogravimetric analysis (TGA) [17]. However, although the analysis of PCT has been extensively studied, to our knowledge few works based on electrochemical methods using modified electrodes have been developed [18–20]. In addition, the electrochemical methods are very simple, highly sensitive and low apparatus cost than other traditional methods [21]. It is noteworthy, that the modified electrodes show a high sensitivity and selectivity toward the determination of PCT [22,23] than the unmodified ones [24]. The low biodegradability of PCT motivates us to develop the redox methods favoring its electrochemical activity. Indeed, the electrocatalytic reduction or oxidation can be advantageously applied to the extensive treatment of real matrices to detect and eliminate PCT. Consequently, a suitable catalyst is of great interest in real applications and it can be used to accelerate the reduction of PCT with a significant increase of the reduction currents and a shift of potentials towards less negative values.
http://dx.doi.org/10.1016/j.jtice.2016.06.013 1876-1070/© 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 1. (A) CVs of 1.0 × 10−4 mol/L PCT on the (a) CPE and (b) FAP−CPE at scan rate of 50 mV/s in 0.1 mol/L PBS (pH 7.0). (B) Square wave voltammograms of 1.0 × 10−4 mol/L PCT in 0.1 mol/L PBS at (a) CPE and (b) FAP−CPE (FAP/CP of (6/4: w/w).
Continuing with our interest in the use of fluoroapatite (FAP) as a carbon paste modified electrodes having sensing probes toward the oxidation or reduction of various electroactive species [25,26]. Among the different inorganic solids, FAP has advantages because it is cheap, readily available, stable in water, non-toxic, not a pollutant and, in particular, the fluorapatite is reputed unanimously for their weak solubility [27], herein we report an efficient and pertinent method for the electroreduction of PCT using square wave voltammetry. This methodology has been successfully applied to construct an enhanced sensing platform for the electrochemical detection of PCT in natural water samples, commercial tablets and human urines without any sample pre-purification steps. 2. Experimental 2.1. Reagents All chemicals used were of analytical grade or of the highest purity available. FAP [28], sodium hydroxide, sodium phosphate dibasic, monosodium phosphate and chloridric acid were purchased from commercial sources and used as received. Paracetamol (Malinkroute, 99.99%) was dissolved in phosphate buffer solution (0.1 mol/L) to prepare stock solutions of 1.0 × 10−3 mol/L. Then the working standard solutions were prepared by successive dilution of the stock solutions by sodium sulfate. Carbon paste was supplied from Carbone, Lorraine, ref 9900, France. All the reagents used were of analytical grade. Distilled water (DW) was used throughout the preparation of the solutions. 2.2. Instrument Electrochemical measurements were carried out by using an eDAQ e-corder/potentiostat EA163 controlled by eDAQ EChem data acquisition software and equipped with three electrode system mounted on cell. Working electrode was FAP-modified carbon paste electrode, the counter electrode was a platinum plate and Ag/AgCl/Cl− (3 mol/L) served as reference. The pH-meter (Radiometer, sensIONTM , PH31, Spain) was used for adjusting pH values. The electrochemical impedance measurements were done via an electrochemical impedance analyzer potentiostat (model PGZ 100, Eco Chemie B.V., Utrecht, The Netherlands) using a computer controlled by voltalab master 4 software logiciel.
2.3. Preparation of the chemically modified electrode The modified carbon-paste electrode was prepared by mixing the graphite powder with the fluoroapatite to give a ratio FAP/CP of (6/4 : w/w). Portions of the resulting composite material were then packed into a home built electrode assembly consisting of the cavity (geometric area 0.1256 cm2 ) of PTFE cylindrical tube electrode of a plastic pipette tip. Electrical contact was established with a bar of carbon. 2.4. Electrochemical measurements A glass cell was washed with 10% hydrochloric acid then rinsed with DBW. Two-step procedures were followed for the analytical determination of PCT in aqueous samples. At open circuit, the working electrode was first immersed in 0.1 mol/L phosphate buffer solution (PBS) containing PCT. Where the accumulation of PCT was achieved chemically, the square wave experiments were performed in PBS electrolyte solutions at FAP–CPE. The potential range was performed from 0.0 mV to 500 mV with a frequency of 30 Hz, pulse height of 40 mV and modulation amplitude 5 mV at scan rate 150 mV/s. The cyclic voltammogram was recorded between −0.4 and −1.0 V. EIS was performed between 100 kHz and 100 mHz at AC amplitude of 10 mV. All measurements were performed at room temperature. 2.5. HPLC analysis of paracetamol The chromatographic separation was applied using a mobile phase of water and methanol (20/80), through a Nucleosil 1005 C18 (250 × 4.6 mm I.D. 5 μm) column (Macherey-Nagel, Germany), with an injection volume of 10 μl, and a flow rate set to 1.0 mL/min. The detector responses were measured in terms of peak area, using the Borwin chromatographic software for storage, and data mining process. 3. Results and discussion 3.1. Electrocatalytic behaviors of PCT at FAP−CPE 3.1.1. Comparisons between CPE and FAP−CPE The electrochemical response of 1.0 × 10−4 mol/L PCT in 0.1 mol/L phosphate buffer (pH 7) at the working electrodes have been studied by using cyclic voltammetry (Fig. 1A). On the unmodified CPE (Fig. 1Aa), PCT shows a quasi-reversible redox. In the case
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 2. CVs of 1.0 × 10−4 mol/L PCT on FAP−CPE at different scan rates (1, 5, 10, 50, 100, 160, 200, 250 and 320 mV/s) in 0.1 mol/L PBS (pH 7.0). Inset, the plot of the peak current vs. scan rate.
of FAP−CPE, a pair of well-defined and reversible redox peaks corresponding to the electrochemical reaction of PCT was obtained, with Epa = 446 mV and Epc = 330 mV. It can be seen that the reduction over potential of PCT becomes higher than that on CPE with a positive shifting of 314 mV. An Epa shifted toward negative potentials in the presence of the fluoroapatite (Fig. 1Bb) was shown. The results demonstrated that the electrochemical reactivity of PCT is remarkably improved on the FAP−CPE. Owing to its high adsorptivity and good biocompatibility, FAP particles effectively modify the surface chemistry of carbon, which provides an efficient interface and microenvironment for the electrochemical reaction of PCT. Results confirm that the FAP can catalyze paracetamol oxidation, this was possible thanks to their structure, the presence of Brønsted acid sites and Lewis and their ability to make exchanges ion. In the square wave voltammetric, the oxidation peak currents of paracetamol on the FAP–CPE were about 80 fold higher than that of the unmodified electrodes (Fig. 1B). 3.1.2. Effect of scan rate The scan rate effect on the anodic and cathodic peak current of PCT on the FAP−CPE was investigated. As shown in Fig. 2, the anodic and cathodic peak currents increase as the scan rate grows from 5 to 250 mV/s. The linear relationship between the peak current and square root of scan rate can be expressed by the linear regression equations as: Ipa/μA = 8.16(v)1/2 −12.62 (R² = 0.982) and Ipc/μA = −2.39(v)1/2 −4.30 (R² = 0.988), respectively. According to the literature, the results indicate that the electrochemical reaction of PCT on the FAP−CPE is a surface-controlled process [29,30]. In addition, Epc is shifted to positive potentials, while Epa is neg-
atively shifted. This can be due to changes in the electroactivity and kinetic effect of FAP−CPE surface on the reduction of PCT especially at scan rates lower than 5 mV/s. In other words, at scan rates lower than 5 mV/s the time window for the PCT oxidation becomes very narrow, avoiding the facile electron transfer between substrate and catalytic sites. At high scan rates ranging from 1 to 320 mV/s, plotting the Epa and Epc vs. lnv produces a straight line with the linear regression equations as: Epa = 0.032 ln(v) + 0.276 (R² = 0.958) and Epc = −0.027ln(v) + 0.475 (R² = 0.996), respectively. According to Laviron’s equation [31], the slops of the lines are equal to RT/α nF and −RT/α nF, respectively. Therefore, the electron transfer coefficient (α ) and the electron transfer number (n) are calculated to be 0.54 and 2, respectively. The adsorbed amount of PCT on the surface of FAP−CPE was further calculated by the following equation: ip = n2 F2 A Гv/4RT [31]. Based on the relationship of ip with v, the value of the surface concentration of the PCT (Г) was obtained with the results as 4.54 × 10−8 mol/cm2 . This high surface concentration can be attributed to the FAP modifier. 3.1.3. Effect of pH Fig. 3 represents CVs of the modified electrode in 1.0 × 10−4 mol/L PCT at various pH values. A decrease in pH of the solution from 12.0 to 2.0 led to a positive shift in both reduction and oxidation peak potentials. So the peak potentials seem to be affected by the concentration of H+ , suggesting the presence of protonation step in the electrochemical mechanism as indicated in Schema 1. However, there was no considerable decrease in the peak currents. These results indicated that the slope was 45.0 ± 0.65 mV/pH over a pH range of 2.0 to 12.0. This
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 3. CVs of FAP–CPE at different pH values: 2.0–12.0; 1.0 × 10−4 mol/L in 0.1 mol/L PBS; Plot of Epc vs. pH value.
O
O HN
C
N
CH3
C
CH3
- 2H+ - 2e-
OH
O Schema 1. Proposed mechanism of PCT reduction.
used to evaluate the electrocatalytic effect of the fluoroapatite. Fig. 4 represents the current-time profiles obtained by setting the working electrode potential. As seen, the behavior is typical of that expected for a mediated reduction. We found that cathodic current of the PCT on FAP−CPE is still higher than that measured on the unmodified carbon paste electrode, indicating that electrode FAP−CPE has high catalytic ability to reduce PCT. This confirms the results previously obtained by cyclic voltammetry. The performance of PCT reduction on the FAP−CPE reached 50% compared to CPE. The results obtained by chronoamperometry, show that electrode FAP−CPE can effectively catalyze the reduction of PCT. 3.3. Electrochemical impedance spectroscopy studies
value was smaller than the ideal Nernst’s value of 59.2 mV/pH for a two electron and two proton process [32]. According to the literature, we can predict that the mechanism depicted in Schema 1, seemed to be proposed for the reduction of PCT [33–36]. This behavior is due to the contribution of H+ ions and the structural changes in –OH– and –NHCOCH3 groups of PCT which get involved in the reduction process of paracetamol [37,38]. Therefore, pH 7.0 was selected as the optimum pH for the electrochemical determination of PCT, which is close to the physiological conditions.
Fig. 5 shows Nyquist plots of 1.0 × 10−4 mol/L in the 0.1 mol/L PBS at these electrodes within the frequency range of 100 kHz to 100 mHz at the formal potential of the redox probe. The almost straight line plots obtained implies the low charge transfer resistance of the redox probe [39,40]. At high frequencies, CPE (curve a) experiences a sharp increase of Zim and behaves closer to an ideal capacitor [41]. The presence of a small and depressed semicircle in curve (b) at lower frequencies could be due to the charge-transfer resistance (Rct) of the electrodes. The FAP–CPE has a higher Rct which implies that the interfacial resistance has increased. This result explains the fixation of the paracetamol onto electrode surface.
3.2. Chronoamperometry studies of PCT at FAP−CPE
3.4. Electroanalytical studies of PCT at FAP−CPE
To confirm the results obtained by cyclic voltammetry, the chronoamperometry as another electrochemical technique was
In order to quantify PCT, experimental conditions has been optimized using the relationships between peak current (IP) and the
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 4. Chronoamperograms obtained of PCT at different reduction potential, 1.0 × 10−4 mol/L in 0.1 mol/L PBS.
Fig. 5. Impedance spectra at 0 V (a) CPE−PCT and (b) FAP−CPE−PCT.
chemical and electrochemical parameters. All these parameters exert an intense effect on the peak current. An increasing of the pulse height from 10 to 70 mV led to the increase of peak currents of PCT. However, after 40 mV, it caused peak broadening. Therefore, a value of 40 mV was chosen as optimal pulse height for further studies. The influence on the frequency of the current intensity of PCT was evaluated in the range of 5 to 40 Hz (Fig. 6). The signal increases with the increase of the frequency. Thus, in further experiments a value of 30 Hz, corresponds to 0.033 s of duration for each step, was employed to ensure the maximum diffusion of the electro-active species to electrode surfaces. We can assume that
the redox process involves the adsorption as the rate-determining step [42]. This behavior is typical of the responses obtained at electrodes, where the electroactive species interact with working electrode, in the adsorption process, before the redox reaction occurs. The results confirm those obtained by varying the scan rate in cyclic volammetry. We have also investigated the amplitude influence in the range from 1 to 15 mV. The results obtained demonstrated that a height of PCT peak increased linearly as a consequence of the increase in amplitude values up to 5 mV. In agreement with the high peak current values, good shapes of the signal and better signal to noise ratio were obtained, the selected optimal values were 30 Hz, 40 mV and 5 mV for frequency, modulation amplitude and pulse height respectively. The effect of pH on the determination of PCT in PBS solution at the FAP–CPE was carefully investigated in the pH range of 3.0– 8.0. The anodic peak current of PCT increases with increasing pH values until the pH reaches 6.8–7.0, the anodic peak current then decreases with further increases in the pH. The maximum anodic peak current appeared at pH 7.0. Therefore, PBS with a pH of 7.0 was selected for all subsequent electrochemical PCT analyses. Accumulation time is an important parameter for SWV technique and has a non-negligible influence on the sensitivity of determination of PCT (Fig. 6). It is clear that the anodic peak intensity increased with the increase of the preconcentration times in the range from 10 s to 600 s, the anodic peak current decreased significantly around 210 s after saturation of electrode surfaces. Taking account of sensitivity and efficiency, accumulation time was 210 s in the following experiments. The square wave voltammograms (Fig. 6) demonstrated that the increase of the concentration of fluoroapatite as modifier (from 10 to 80% by weight of carbon paste), affects the electrochemical behaviors of PCT at the carbon paste electrode. The peak currents
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Fig. 6. Influence of the experimental variables (pulse height, amplitude, frequency, pH, time preconcentration and Percentage FAP/CP) involved in the SWV method and response to PCT 1.0 × 10−4 mol/L in 0.1 mol/L PBS at the FAP−CPE.
of PCT increase with the increase of the modifier amount. Moreover, the intensity of peak decreases if the concentration of modifier is higher than 60% of FAP loading by weight (w/w). This result is probably due to the decrease in the modified electrode conductivity. In the course of the study, a modifier concentration of about 60% of the ratio FAP/CP is used.
3.5. Linear range and detection limit The calibration curve for the SWV peak current for PCT oxidation vs. PCT concentration shows excellent linearity over a wide concentration range from 1.0 × 10−3 to 4.0 × 10−8 mol/L (Fig. 7). It can be seen that the calibration plots of peak current vs. concentration of PCT show two linear dynamic ranges from 1.0 × 10−3 –4.0 × 10−5 mol/L and 2.0 × 10−5 –4.0 × 10−8 mol/L (Fig. 7). The linear regression equations for these two regions are ipa(μA) = 0.037 [PCT] (mol/L) + 124.1 (R² = 0.977) and ipa(μA)=3.238[PCT] (mol/L) + 25.73 (R² = 0.990). The standard deviation of the mean current (sb) measured at the oxidation potential of paracetamol for 10 voltammograms of the blank solution in pure electrolytes was used [43] in the determination of the quantification limit (LOQ, 10 s) and the detection limit (LOD, 3 s) together with the slope of the straight line of the analytical curves. The limit of detection (DL) and limit of quantification (QL) are calculated to be respectively 1.25 × 10−8 mol/L and 4.16 × 10−8 mol/L. The precision (n = 8) assessed as relative standard deviation (R.S.D.) were 1.24% for 1.0 × 10−6 mol/L and 1.07% for 4.0 × 10−6 mol/L, respectively. The electrochemical behavior of FAP−CPE for PCT was contrasted with some of the previously reported electrodes (Table 1). It is obvious that PCT at FAP−CPE showed a low relative standard deviation, broad linearity range, and a low detection limit.
The FAP−CPE electrode here could maintain its activity as a sensor for parectamol during 4 months; the response was 97.15% of its initial value which shows long-term stability and very good sensitivity for the analysis of paracetamol. 3.6. Effect of interferents In order to evaluate the selectivity of the prepared sensor, the effect of various possible interferents on the determination of PCT was examined, and the results were summarized in Table 2. It was observed that Na+ , Mg2+ , Ca2+ , Cu2+ , Pb2+ , Cd2+ , K+ , Ni2+ , Co3+ , Zn2+ , Al3+ , Fe3+ , Fe2+ , V5+ , Cr3+ , NO3 − , showed no obvious interference for the determination of 1.0 × 10−5 mol/L PCT even when present 100 times in excess, with deviations below 4%. However, Ag+ was found to affect the detection of PCT. It was found that 100-fold of Ag+ interfered with the determination of 1.0 × 10−5 mol/L PCT (peak current change 5.83%). The influences of the presence of organic elements on the PCT signals were also tested. At the same concentration, ascorbic acid, citric acid, ibuprofen and dopamine had no apparent effects on the current response of PCT (˂2%). Electrochemically active ascorbic acid (vitamin C) is often combined with PCT based drugs. No significant interference effect was observed in the developed SWV method up to 10 fold concentration of ascorbic acid (Ep ≈ −200 mV) in comparison with concentration of PCT (Ep ≈ +400 mV). As in the case of ascorbic acid, no significant interference effect of dopamine (Ep ≈ +200 mV) was observed under the same conditions. Both these results indicate the possibility of eventual determination of PCT simultaneously with ascorbic acid or dopamine. 3.7. Practical application In order to evaluate the performance of FAP−CPE by practical analytical applications, the determination of PCT was carried out in
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Fig. 7. SWV curves of different concentrations of PCT in 0.1 mol/L PBS (pH 7) at FAP−CPE: 1.0 × 10−3 – 4.0 × 10−5 mol/L and 2.0 × 10−5 −4.0 × 10−8 mol/L.
Table 1 Comparison of the electrochemical behavior of PCT at FAP−CPE with some of the previously reported electrodes. Methods Cu-PTTCA/GCE VCPTE Nafion/GCE GCE CILE C60/GCE PANI-MWCNTs/GCE C–Ni/GCE PAY/nano-TiO2 /GCE FAP-CPE
Linear range (μmol/L) 20–50 0 0 0.120–5800 50–500 2–1580 1.0–20 0 0 50–1500 1–100 2–230 12–120 10 0 0–4.0 0 and 200–0.04
DL (mol/L) −6
5.0 × 10 88.0 × 10−6 17.0 × 10−6 19.0 × 10−6 0.3 × 10−6 0.5 × 10−4 2.5 × 10−7 6.0 × 10−7 2.0 × 10−6 1.25 × 10–8
DSR (%)
Refs
– – – – – – 3.9 1.1 – 1.07
[44] [45] [46] [47] [48] [49] [50] [51] [52] Present work
Cu-PTTCA/GCE: Cu-poly terthiophene carboxylic acid modified glassy carbon electrode. VCPTE: Vaseline carbon paste tissue electrode. Nafion/GCE: Nafion modified glassy carbon electrode. GCE: Glassy carbon electrode. CILE: carbon ionic liquid electrode. PAYnano-TiO2 /GCE: poly(acid yellow 9)/nano-TiO2 modified glassy carbon electrode. C60/GCE: C60-modified glassy carbon electrode. PANI-MWCNTs/GCE: A polyaniline–multi-walled carbon nanotubes (PANI–MWCNTs) composite modified electrode. C–Ni/GCE: A novel type of carbon-coated nickel magnetic nanoparticles modified glass carbon electrodes.
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Y. EL Bouabi et al. / Journal of the Taiwan Institute of Chemical Engineers 000 (2016) 1–10 Table 2 Influence of coexisting substances on the determination of 1.0 × 10−4 mol/L PCT (n = 3). Coexisting substance +
Na Mg2+ Ca2+ Cu2+ Pb2+ Cd2+ K+1 Ni2+ CO2+ Zn2+ Ag+
Concentration (mmol/L)
Change of peak current (%)
3+
−1.27 −1.65 −1.89 −1.20 1.48 −1.47 0.85 0.55 −0.28 −1.42 −5.83
1 1 1 1 1 1 1 1 1 1 1
Coexisting substance Al Fe3+ Fe2+ V5+ Cr3+ NO3 − Ibuprofen Ascorbic acid Citric acid Dopamine
Concentration (mmol/L)
Change of peak current (%)
1 1 1 1 1 1 0.1 0.1 0.1 0.1
0.45 0.56 0.67 1.52 0.22 −1.27 −0.40 −1.72 −1.5 −1.06
Fig. 8. Curves calibration of the determination of PCT in: (a) seawater (b) river water. Table 3 Determination of PCT in water samples and human urines. (FAP-CPE) Samples
PCT Added (×10
River water River water Sea water Sea water Human urines Human urines Human urines
2 4 2 4 2 4 6
−5
mol/L)
PCT found (×10
(HPLC) −5
1.94 3.96 1.92 3.95 1.90 3.92 5.91
mol/L)
Recovery (%)
PCT found (×10−5 mol/L)
Recovery (%)
97.00 ± 9.45 99.00 ± 5.74 96.00 ± 11.31 98.75 ± 6.41 95.00 ± 12.58 98.00 ± 8.08 98.50 ± 7.01
1.96 3.99 1.98 3.97 1.95 3.94 5.99
98.00 99.75 99.00 99.25 97.50 98.50 99.83
All samples were analyzed using standard addition method (n = 3). √ ∗ Extended DPV-recovery (R) = ± (R0 (1 − R0 )/n (n = 3), where R0 is the percentage recovery, t is a distribution value chosen for the desired confidence level. Theoretical values at 95% confidence limits: t = 2.78.
real samples (river water, seawater, commercial tablets and human urines). (i) River water and seawater The experiments were carried out by adding a known amount of PCT to the support electrolyte followed by standard additions from the PCT stock solution and plotting the resulting analytical curve. The support electrolytes were prepared by addition of 0.1 mol/L of PBS to a fresh water samples. The plot of peak currents against PCT concentration was linear (Fig. 8). The results of the determination of PCT using calibration curves are given in Table 3. No
interference of the matrix components was observed even without any sample pretreatment. No signal for PCT was observed when the water samples were analyzed, which may be attributed to that no PCT is in water samples or the concentration of PCT is lower than the detection limit. (ii) Determination of PCT in urine samples FAP–CPE is investigated for the measurement of PCT in three human urine samples. The percentage of recovery of the spiked sample is in the range between 98.00 and 98.50. The results obtained by this method agreed with those by the HPLC. The result
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013
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Table 4 Determination results of PCT in tablets by FAP−CPE (n = 5). (FAP–CPE)
(HPLC)
Sample
Label (mg/tablet)
PCT found (mg/tablet)
RSD (%)
Recovery (%)
PCT found (mg/tablet)
Recovery (%)
Doliprane Panadol
10 0 0 500
980 489
1.85 1.74
98.00 97.80
985 491
98.50 98.20
in Table 3 was mean value of replicating measurement of three times. Model human urine samples were used to demonstrate that matrix components do not interfere with PCT determination. The results show that the modified electrode is suitable for the determination of PCT in biological fluids (iii) Determination of PCT in formulation tablets The developed method was applied to the analysis of two different commercial tablets. The tablets were weighed, ground into powder, and then dissolved in 0.1 PBS mol/L adequately. All the sample solutions were transferred to 25 mL flask and diluted with PBS (pH 7.0). The mean percentage recoveries of added PCT were found to be 97.80% and 98.00% using the proposed method and HPLC, respectively (Table 4). There were no significant differences between the recoveries calculated at the 95 % confidence level and within an acceptable range error of 5%. The excellent average recoveries of formulation tablets samples suggest that the FAP−CPE developed in this work has practical significance and is able to determine PCT in formulation tablets. 4. Conclusion A highly advanced and sensitive FAP−CPE toward PCT reduction has been disclosed. The performances of FAP−CPE were significantly better than those of CPE because it exhibited a remarkably enhanced electrocatalytical activity toward the sensing of PCT. The influence of the experimental variables which involved in the SWV determination of PCT was investigated. Analytical results show that the proposed modified electrode was able to detect 1.25 × 10−8 mol/L of PCT with good sensitivity and repeatability. Results of voltammetric determination of PCT in real samples were in good agreement with those of HPLC methods proving that FAP−CPE offers a useful and reliable method for the quantification of PCT in real samples. Acknowledgments The authors wish to express their appreciation to the Hassan 1er University. This study could not have been conducted without their financial supports. References [1] Sun D, Zhang H. Electrochemical determination of acetaminophen using a glassy carbon electrode coated with a single-wall carbon nanotube-dicetyl phosphate film. Microchim Acta 2007;158:131–6. [2] Yin H, Shang K, Meng X, Ai S. Voltammetric sensing of paracetamol, dopamine and 4-aminophenol at a glassy carbon electrode coated with gold nanoparticles and an organophilliclayered double hydroxide. Microchim Acta 2011;175:39–46. [3] Tsierkezos NG, Othman SH, Ritter U. Nitrogen-doped multi-walled carbon nanotubes for PCT sensing. Ionics 2013;19:1897–905. [4] Lourenção BC, Medeiros RA, Rocha-Filho RC, Mazo LH, Fatibello-Filho O. Simultaneous voltammetric determination of PCT and caffeine in pharmaceutical formulations using a boron-doped diamond electrode. Talanta 2009;78:748–52. [5] Sultan MA, Maher HM, Alzoman NZ, Alshehri MM, Rizk MS, Elshahed MS, et al. Capillary electrophoretic determination of antimigraine formulations containing caffeine, ergotamine, PCT and domperidone or metoclopramide. Chromatogr Sci Ser 2013;51:502–10.
[6] Abdelaleem EA, Abdelwahab NS. Validated stability indicating RP-HPLC method for determination of PCT, methocarbamol and their related substances. Anal Methods 2013;5:541–5. [7] Wilson JM, Slattery JT, Forte AJ, Nelson SD. Analysis of acetaminophen metabolites in urine by high performance liquid chromatography with UV and amperometric detection. J Chromatogr B Biomed Sci Appl 1982;227:453–62. [8] Ravisankar S, Vasudevan M, Gandhimathi M, Suresh B. Reversed-phase HPLC method for the estimation of acetaminophen, ibuprofen and chlorzoxazone in formulations. Talanta 1998;46:1577–81. [9] Modick H, Schütze A, Pälmke C, Weiss T, Brüning T, Koch HM. Rapid determination of N-acetyl-4-aminophenol (paracetamol) in urine by tandem mass spectrometry coupled with on-line clean-up by two dimensional turbulent flow/reversed phase liquid chromatography. J Chromatogr B Analyt Technol Biomed Life Sci 2013;925:33–9. [10] Roy J, Saha P, Sultana S, Kenyon AS. Rapid screening of marketed paracetamol tablets: use of thin-layer chromatography and a semi quantitative spot test. Bull World Health Organ 1997;75:19–22. [11] Abirami G, Vetrichelvan T. simultaneous determination of tolperisone and paracetamol in pure an fixed dose combination by UV-Spectrophotometry. Int J Pharm Pharm Sci 2013;5:488–92. [12] Canada MJA, Reguera MIP, Medina AR, De Cordova MLF, Diaz AM. Fast determination of paracetamol by using a very simple photometric flow-through sensing device. J Pharm Biomed Anal 20 0 0;22:59–66. [13] Srivastava MK, Ahmed S, Singh D, Shukla IC. Titrimetric determination of dipyrone and paracetamol with potassium hexacyanoferrate (III) in an acidic medium. Analyst 1985;110:735–7. [14] Vilchez JL, Blanc R, Avidad R, Navalon A. Spectrofluorimetric determination of paracetamol in pharmaceuticals and biological fluids. J Pharm Biomed Anal 1995;13:1119–25. [15] Knochen M, Giglio J, Reis BF. Flow-injection spectrophotometric determination of paracetamol in tablets and oral solutions. J Pharm Biomed Anal 2003;33:191–7. [16] Ramos ML, Tyson JF, Curran DJ. Determination of acetaminophen by flow injection with on-line chemical derivatization: investigations using visible and FTIR spectrophotometry. Anal Chim Acta 1998;364:107–16. [17] Khanmohammadi M, Soleimani M, Morovvata F, Garmarudi AB, Khalafbeigi M, Ghasemi K. Simultaneous determination of paracetamol and codeine phosphate in tablets by TGA and chemometrics. Thermochim Acta 2012;530:128–32. [18] Pedrosa VA, Lowinsohn D, Bertotti M. FIA determination of paracetamol in pharmaceutical drugs by using gold electrodes modified with a 3-mercaptopropionic acid monolayer. Electroanalysis 2006;18:931–4. [19] Radovan C, Cofan C, Cinghita D. Simultaneous determination of acetaminophen and ascorbic acid at an unmodified boron-doped diamond electrode by differential pulse voltammetry in buffered media. Electroanalysis 2008;20:1346–53. [20] Li M, Jing L. Electrochemical behavior of acetaminophen and its detection on the PANI–MWCNTs composite modified electrode. Electrochim Acta 2007;52:3250–7. [21] Lau OW, Luk SF, Cheung YM. Simultaneous determination of ascorbic acid, caffeine and paracetamol in drug formulations by differential-pulse voltammetry using a glassy carbon electrode. Analyst 1989;114:1047–51. [22] Xu ZM, Yue Q, Zhuang ZJ, Xiao D. Flow injection amperometric determination of acetaminophen at a gold nanoparticle modified carbon paste electrode. Microchim Acta 2009;164:387–93. [23] Teixeira MFS, Marcolino LH, Fatibello O, Moraes FC, Nunes RS. Determination of analgesics (dipyrone and acetaminophen) in pharmaceutical preparations by cyclic voltammetry at a copper(II) hexacyanoferrate(III) modified carbon paste electrode. Curr Anal Chem 2009;5:303–10. [24] Skeika T, De Faria MF, Nagata N, Pessoa CA. Simultaneous voltammetric determination of dypirone and paracetamol with carbon paste electrode and multivariate calibration methodology. J Braz Chem Soc 2008;19:762–8. [25] Hidalgo-Carrillo J, Sebti J, Aramendía MA, Marinas A, Marinas JM, Sebti S, et al. A study on the potential application of natural phosphate in photocatalytic processes. J Colloid Interf Sci 2010;344:475–81. [26] Sebti S, Zahouily M, Lazrek HB, Mayoral JA, Macquarrie DJ. Phosphates: new generation of liquid-phase heterogeneous catalysts in organic chemistry. Curr Org Chem 2008;12:203–32. [27] Vieillard P, Tardy Y, Nriagu JO, Moore PB. Phosphate minerals. New York: Springer-Verlag; 1984. [28] El Mhammedi MA, Bakasse M, Chtaini A. Investigation of square wave voltammetric detection of diquat at carbon paste electrode impregnated with Ca10 (PO4 )6F2 : application in natural water samples. Mater Chem Phys 2008;109:519–25.
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ARTICLE IN PRESS
[m5G;June 28, 2016;19:8]
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[29] Dalmasso PR, Pedano ML, Rivas GA. Electrochemical determination of ascorbic acid and paracetamol in pharmaceutical formulations using a glassy carbon electrode modified with multi-wall carbon nanotubes dispersed in polyhistidine. Sens Actuators: B Chem 2012;173:732–6. [30] Lu TL, Tsai YC. Sensitive electrochemical determination of acetaminophen in pharmaceutical formulations at multiwalled carbon nanotube-alumina– coated silica nanocomposite modified electrode. Sens Actuators: B Chem 2011;153:439–44. [31] Laviron E. General expression of the linear potential sweep voltammogram in the case of diffusion less electrochemical systems. J Electroanal Chem 1979;101:19–28. [32] Rahimi P, Rafiee-Pour H, Ghourchian H, Norouzi P, Ganjali MR. Ionic-liquid/ NH2-MWCNTs as a highly sensitive nano-composite for catalase direct electrochemistry. Biosens Bioelectron 2010;25:1301–6. [33] Ghorbani-Bidkorbeh F, Shahrokhian S, Mohammadi A, Dinarvand R. Simultaneous voltammetric determination of tramadol and acetaminophen using carbon nanoparticles modified glassy carbon electrode. Electrochim Acta 2010;55:2752–9. [34] Zidan M, Tan W, Abdullah AH, Zainal Z, Goh JK. Electrocatalytic oxidation of paracetamol mediated by lithium doped microparticles Bi2 O3 /MWCNT modified electrode. Asian J Chem 2011;23:3029–32. [35] Li C, Zhan G, Yang Q, Lu J. Electrochemical Investigation of acetaminophen with a carbon nano-tube composite film electrode. Bull Korean Chem Soc 2006;27:1854–60. [36] Sotomayor M, Sigoli A, Lanza MRV, Tanaka AA, Kubota LT. Construction and application of an electrochemical sensor for paracetamol determination based on iron tetrapyridinoporphyrazine as a biomimetic catalyst of P450 enzyme. J Braz Chem Soc 2008;19:734–43. [37] Su WY, Cheng SH. Electrochemical oxidation and sensitive determination of acetaminophen in pharmaceuticals at poly(3,4-ethylenedioxythiophene)modified screen-printed electrodes. Electroanalysis 2010;22:707–14. [38] Manjunatha R, Nagaraju DH, Suresh GS, Melo JS, D’Souza SF, Venkatesha TV. Electrochemical detection of acetaminophen on the functionalized MWCNTs modified electrode using layer-by-layer technique. Electrochim Acta 2011;56:6619–27. [39] Luo J, Jiang S, Zhang H, Jiang J, Liu X. A novel non-enzymatic glucose sensor based on Cu nanoparticle modified graphene sheets electrode. Anal Chim Acta 2012;709:47–53.
[40] Fan H, Li Y, Wu D, Ma H, Mao K, Fan D, et al. Electrochemical bisphenol A sensor based on N-doped grapheme sheets. Anal Chim Acta 2012;711:24–8. [41] Tehrani RMA, Ab Ghani S. MWCNT-ruthenium oxide composite paste electrode as non-enzymatic glucose sensor. Biosens Bioelectron 2012;38:278–83. [42] Lovric M, Komorsky-Lovric S. Square-wave voltammetry of an adsorbed reactant. J Electroanal Chem 1988;248:239–53. [43] Mocak J, Bond AM, Mitchel S, Scollary GA. Statistical overview of standard (IUPAC and ACS) and new procedures for determining the limits of detection and quantification: application to voltammetric and stripping techniques. Pure Appl Chem 1997;69:297–328. [44] Boopathi M, Won MS, Shim YB. A sensor for acetaminophen in a blood medium using a Cu(II)-conducting polymer complex modified electrode. Anal Chim Acta 2004;512:191–7. [45] Fatibello-Filho O, Lupetti KO, Vieira IC. Chronamperometric determination of paracetamol using an avocado tissue (Persea Americana) biosensor. Talanta 2001;55:685–92. [46] Silva MLS, Garcia MBQ, Lima JLFC, Barrado E. Modified tubular electrode in a multi-commutated flow system: determination of acetaminophen in blood serum and pharmaceutical formulations. Anal Chim Acta 2006;573–574:383–90. [47] Tungkananuruk K, Tungkananuruk N, Burns DT. Cyclic voltammetric determination of acetaminophen in paracetamol tablets. KMITL Sci Technol J 2005;5:547–51. [48] ShangGuan X, Zhang H, Zheng J. Electrochemical behavior and differential pulse voltammetric determination of paracetamol at a carbon ionic liquid electrode. J Anal Chem 2008;391:1049–55. [49] Goyal RN, Singh SP. Voltammetric determination of paracetamol at C60-modified glassy carbon electrode. Electrochim Acta 20 06;51:30 08–12. [50] Mingqi L, Linhai J. Electrochemical behavior of acetaminophen and its detection on the PANI–MWCNTs composite modified electrode. Electrochim Acta 2007;52:3250–7. [51] Wang SF, Xie F, Hu RF. Carbon-coated nickel magnetic nanoparticles modified electrodes as a sensor for determination of acetaminophen. Sens Actuators: B Chem 2007;123:495–500. [52] Kumar SA, Tang CF, Chen SM. Electroanalytical determination of acetaminophen using nano-TiO2 /polymer coated electrode in the presence of dopamine. Talanta 20 08;76:997–10 05.
Please cite this article as: Y. EL Bouabi et al., Electrocatalytic effect of fluoroapatite in reducing paracetamol at carbon paste electrode: Analytical application, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.06.013