Amplified nanostructure electrochemical sensor for simultaneous determination of captopril, acetaminophen, tyrosine and hydrochlorothiazide

Materials Science and Engineering C 73 (2017) 472–477

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Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec

Amplified nanostructure electrochemical sensor for simultaneous determination of captopril, acetaminophen, tyrosine and hydrochlorothiazide Hassan Karimi-Maleh a,⁎, Mohammad R. Ganjali b, Parviz Norouzi b, Asma Bananezhad b a b

Department of Chemistry, Graduate University of Advanced Technology, Kerman, Iran Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran, Iran

a r t i c l e

i n f o

Article history: Received 2 November 2016 Received in revised form 16 December 2016 Accepted 19 December 2016 Available online 21 December 2016 Keywords: Captopril Acetaminophen Tyrosine Hydrochlorothiazide, NiO/CNTs nanocomposite

a b s t r a c t A novel nanomaterial-based voltammetric sensor has been developed for use a highly sensitive tool for the simultaneous determination of captopril (CA), acetaminophen (AC), tyrosine (TY) and hydrochlorothiazide (HCTZ). The device is based on the application of NiO/CNTs and (2-(3,4-dihydroxyphenethyl)isoindoline-1,3-dione) (DPID) to modify carbon paste electrodes. The NiO/CNTs nanocomposite was synthesized through a direct chemical precipitation approach and was characterized with X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The NiO/CNTs/DPID/CPEs were found to facilitate the analysis of CA, AC, TY and HCTZ in the concentration ranges of 0.07–200.0, 0.8–550.0, 5.0–750.0 and 10.0–600.0 μM with the respective detection limits of 9.0 nM, 0.3 μM, 1.0 μM and 5.0 μM. The developed NiO/CNTs/DPID/CPEs were used for the determination of the mentioned analytes in pharmaceutical and biological real samples. © 2016 Elsevier B.V. All rights reserved.

1. Introduction Captopril and hydrochlorothiazide are two important pharmaceuticals used individually or together for treating hypertension [1–3]. These compounds have found other applications in the treatment of congestive heart failure and swelling. On the other hand, acetaminophen has been found to decrease the effects of CAP by opposing drug effects. Recent studies have confirmed that nitrated tyrosine (TY) residues and acetaminophen (AC) adducts can be found in necrotic cells after being subjected to toxic doses of AC [4]. In this light, the development of highly sensitive and selective analytical sensors which can be used for the simultaneous determination of CA, AC, TY and HCTZ is of critical value for the analysis of real samples, yet this has remained a challenge due to the inability of most unmodified sensors to separate the oxidation peak potentials of the mentioned analytes. Applications of modified electrodes are good choice for trace level analysis of biological and pharmaceutical samples [5–11]. In between, carbon paste modified electrodes (CPMEs) have attracted a great deal of attention on the part of electrochemical researchers working in the area of the determination of electro-active compounds. This can in part be due to the superior capability of CPMEs in comparison to other electrodes, including their low cost, low non-faradic currents and simple modification routines [12–18]. CPMEs have been suggested as ⁎ Corresponding author. E-mail address: [email protected] (H. Karimi-Maleh).

http://dx.doi.org/10.1016/j.msec.2016.12.094 0928-4931/© 2016 Elsevier B.V. All rights reserved.

highly sensitive tools for simultaneous determination of electroactive compounds with near over-voltages, in the recent years [19–27]. As an example, Sanghavi and Srivastava reported the application of a carbon-nanotube modified paste electrodes for the simultaneous determination of acetaminophen, aspirin and caffeine in their mixtures [13]. Based on the above mentioned information and in the light of the information presented the current study was based on the development and application of NiO/CNTs/DPID/CPEs for the voltammetric determination of CAP. The developed voltammetric sensor was also found to be able to sense and distinguish signals of CA, AC, TY and HCTZ in mixed samples for the first time. The device further enjoyed advantages including good performance and high sensitivity which made it applicable for use in the determination of CA, AC, TY and HCTZ in tablet and urine samples. 2. Experimental 2.1. Apparatus and materials Captopril, acetaminophen, tyrosine, hydrochlorothiazide, graphite powder, paraffin oil, nickel nitrate, carbon nanotubes and sodium hydroxide were purchased from Sigma-Aldrich Company without any further treatments. Nickel nitrate, carbon nanotubes and sodium hydroxide were used for synthesized of NiO/CNTs nanocomposite according to my previous reported [28]. The crystallinity of the NiO/ CNTs were examined through X-ray diffraction (XRD) using a STOE

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Fig. 1. A) XRD pattern of as-synthesized NiO/CNTs. B) SEM image of as-synthesized NiO/CNTs.

diffractometer with a Cu-Kα radiation source, in the range 20–80° (2θ). For investigating the morphology of the NiO/CNTs nanocomposites a digital scanning electron microscope (YKY-EM3200) was used. All of the electrochemical investigations were performed using an Autolab potentiostat/galvanostat PGSTAT 35 (Eco chemie Utrecht, Netherlands). An Ag/AgCl/KClsat, a platinum wire and the developed NiO/CNTs/DPID/ CPEs were respectively used as the reference, electrode and electrodes. 2.2. Synthesis of DPID In this procedure phthalic anhydride was reacted with 3hydroxytyramine hydrochloride (dopamine hydrochloride) in an acetic acid/pyridine medium under reflux and the product, i.e. DPID was found to have a melting point in the range of 167–168 °C. The chemical structure of the product was studied through common spectroscopic techniques. The FT-IR spectra of the product included characteristic signal bands at 3238, 3051, 2947 , 1768, 1692, 1651, 1612, 1529, 1466, 1433, 1403, 1367, 1266, 1242, 1198, 1152, 1119, 1089, 1003, 952, 870, 531, 494. Further the 1H NMR (CD3OD) spectra showed peaks at 2.84 (t, 2H, CH2CH2N)), 3.85 (t, 2H, CH2CH2N), 6.51 (d, 1H, phenyl), 6.65 (d, 2H, phenyl), and 7.82 (d, 4H, phthalimide) and the 13C NMR (CD3OD) spectra contained peaks at 168.2, 144.9, 133.9, 131.9, 129.6, 122.6, 119.7, 115.5, 114.9, 39.2, and 33.3. Anal. Calcd. for C16H13NO4 (283.08): C, 67.84, H, 4.63, N, 4.94. The yield of the DPID preparation

Fig. 2. Left; SWVs of NiO/CNTs/DPID/CPE at various buffered pHs. The numbers 1–10 correspond to 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0 and 12 pHs, respectively. Right; Plot of Ep vs. pH for NiO/CNTs/DPID/CPE.

process was about 88% and the process revealed great advantages over the previously reported DPID preparation techniques (about 18%). 2.3. Preparation of the sensor To prepare the sensors 10.0 mg of DPID was hand mixed with 890.0 mg of graphite powder and 50.0 mg of NiO/CNTs in a mortar and pestle. Next 12 drops of nujol oil were added to the mixture and it was mixed well for 50 min until a uniformly-wetted paste was obtained. The resulting paste was then packed into a glass tube and an electrical contact was established through inserting a copper wire down the glass tube into the rear side of the paste. 2.4. Preparation of real samples To prepare the tablet samples, eight tablets (from HCTZ, AC and CAP) were grinded to form a uniform powder. Next suitable amounts of the powder were dissolved in 100 mL water samples under sonication.

Fig. 3. Cyclic voltammograms of (a) NiO/CNTs/DPID/CPE in the buffer solution pH = 9.0, (b) DPID/CPE in the presence of 100 μM captopril, (c) NiO/CNTs/DPID/CPE in the presence of 100 μM captopril, (d) NiO/CNT/CPE in the presence of 100 μM captopril, and (e) CPE in the presence of 100 μM captopril. In all cases the scan rate was 10 mV s−1 and pH = 9.0.

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Scheme 1. Suggestion mechanism for electrocatalytic oxidation of captopril at a surface of NiO/CNTs/DPID/CPE.

Then, 1.0 mL of the solution was diluted with a buffer solution (pH = 9.0) in a 10-mLvolumetric flask. Urine samples were centrifuged for 20 min at 2500 rpm, and then filtered using a 0.45 μm filter. Next 1.0 mL of the resulting sample was mixed with 9.0 mL of the buffer (pH = 9.0). 3. Results and discussion

determined to be 17.0 nm, and the peaks were observed at the (111), (200), (220), (311) and (222) planes [28]. The peaks were attributed to the presence of NiO with FCC structure (JCPDS NO. 47-1049). On the other hand, the presence of CNTs was evidently proved by the diffraction peak at about 260. SEM was used to investigate the surface morphological characteristics of NiO/CNTs. Fig. 1B clearly indicates the presence of NiO at the surface of the carbon nanotubes.

3.1. Characterization of NiO/CNTs

3.2. Voltammetric analysis

Fig. 1A shows the XRD patterns of the NiO/CNTs samples synthesized based on the proposed approach. The strongest peaks were used to calculate the grain size of the samples through the Scherrer equation (D = Kλ / (βcosθ) where K is a constant (0.9), λ is the wavelength (λ = 1.5418 Å), β is the full width at the half-maximum of the line and θ is the diffraction angle). The grain size of the NiO nanoparticle was

The effect of pH on the square wave voltammetric (SWV) responses obtained using NiO/CNTs/DPID/CPE working electrodes was also

Fig. 4. Cyclic voltammograms of NiO/CNTs/DPID/CPE in 0.1 mol L−1 PBS (pH 9.0) containing 100 μM captopril at various scan rates; numbers 1–8 correspond to 2.0, 4.0, 8.0, 12.0, 16.0, 20.0, 25.0 and 30.0 mV s−1, respectively. Inset: Variation of anodic peak current vs. v1/2.

Fig. 5. Chronoamperograms obtained at the NiO/CNTs/DPID/CPE (1) in the absence, and in the presence of (2) 100, (3) 150, (4) 200, (5) 300, and (6) 400 μM captopril at pH 9.0. Insets: (a) Plots of I vs. t−1/2 obtained from chronoamperograms 2–6. (b) Plot of the slope of the straight lines against captopril concentration.

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Table 1 Comparison of the efficiencies of some electrochemical methods in the determination of captopril. Electrode

Method

pH

Linear dynamic range (μM)

Limit of detection (μM)

Ref.

Carbon paste electrode Carbon paste electrode Carbon paste electrode Carbon paste electrode Carbon paste electrode Carbon paste electrode Carbon paste electrode Carbon paste electrode

Square wave voltammetry Differential pulse voltammetry Square wave voltammetry Differential pulse voltammetry Square wave voltammetry Square wave voltammetry Square wave voltammetry Square wave voltammetry

7.0 7.0 6.0 8.0 8.0 6.0 8.0 9.0

0.3–140.0 0.8–65.0 0.05–50.0 0.064–320 0.2–400.0 0.05–800 0.09–450 0.07–10.0

0.091 0.3 0.02 0.034 0.08 0.01 0.05 0.009

[32] [33] [34] [1] [35] [36] [3] This work

examined (Fig. 2 left). The oxidation peak signal of the NiO/CNTs/DPID/ CPEs shifted to negative potentials as the pH increased, and a slope of −50.7 mV pH −1 was obtained at 3 b pH b 12 (Fig. 2 right). The slope was very close to the theoretical Nernstian value of − 59.2 mV pH−1, and was consistent with a two electron-two proton mechanism for the electrooxidation of catechol. In order to test the electrocatalytic activity of NiO/CNTs/DPID/CPE in the oxidation of CAP, cyclic voltammograms were acquired using NiO/ CNTs/DPID/CPE, DPID/CPE, NiO/CNTs/CPE and CPE as the working electrodes in the absence and the presence of CAP (Fig. 3). Fig. 3 shows the cyclic voltammograms obtained with NiO/CNTs/DPID/CPE in a buffer solution (pH = 9.0) in the absence (curve a) and the presence of 100.0 μM CAP (curve c). The addition of CAP led to a significant increase in the oxidation peak current while no current could be observed in the reverse scan. The obtained results confirmed an excellent electrocatalytic activity on the part of the NiO/CNTs/DPID/CPE towards CAP (Scheme 1). The voltammetric responses towards a 100.0 μM CAP solution using DPID/ CPE (curve b), NiO/CNTs/CPE (curve d), and CPE (curve e) as the working electrodes are also shown in Fig. 3. A comparison reveals that the oxidation peak potential for CAP at NiO/CNTs/DPID/CPE and DPID/CPE has been 70 mV, while at NiO/CNTs/CPE (curve d) and CPE (curve e) CAP is oxidized at 780 mV. It could be concluded that the application of the

NiO/CNTs/DPID/CPE working electrodes leads to a decreased over-potential as well as an enhanced peak current for CAP samples. To clarify the nature of the electrode reaction involved in the oxidation of CAP, sweep rate (ν) studies were carried out in the range of 2– 30 mV s− 1 (Fig. 4). The linearity of Ip/ν1/2 behavior reveals the that the oxidation for CAP is a diffusion controlled phenomenon (Fig. 4 inset) [23–28]. Chronoamperometry was also used to study the electrocatalytic reactions of CAP and DPID at a surface of the NiO/CNTs/DPID/CPE (Fig. 5) and the result showed that no net cathodic current corresponding to the reduction of the mediator were created in the presence of CAP (when the potential is stepped from the first to the second potential). This is proof of the electrocatalytic interaction between CAP and DPID. The linearity of the ipa / t−1/2 curve further indicates that the current must be controlled by the diffusion of CAP from the bulk solution to the surface of the working electrode (Fig. 5 a). Additionally the slopes of the resulting straight lines were plotted against the concentrations of CAP in the solution (Fig. 5 b), and D was found to be 3.66 × 10−6 cm2/s. The linear dynamic ranges and limits of detection for CAP, AC, TY and HCTZ were obtained for SWV at the surface of NiO/CNTs/DPID/CPE and the results showed the slopes of the Ipa vs. concentrations of CAP, AC, TY and HCTZ were found to be 0.980 μA μM−1 in the range of 0.07–10.0 μM; 0.120 μA μM−1 in the range of 10.0–200.0 μM; 0.0082 μA μM−1 in the

Fig. 6. SWVs of NiO/CNTs/DPID/CPE in 10 μM CAP in the mixed solutions of (from inner to outer): 10.0, 25.0, 50.0, 60.0, 80.0 and 100.0 μM AC, 10.0, 25.0, 60.0, 80.0, and 100.0 μM TY and 10.0, 25.0, 50.0, 80.0, and 100.0 μM HCTZ. Insets show the plots of peak currents as functions of the concentration of: (a) AC in the range 10.0–100.0 μM, (b) TY in the range 10.0–100.0 μM, and (c) HCTZ in the range 10.0–100.0 μM.

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Table 2 Determination of CAP, AC, TY and HCTZ in real samples (n = 5). Sample

CAP added

AC added

TY added

HCTZ added

Found (CAP) Proposed method

Found (CAP) Published paper [1]

Found (AC) Proposed method

Found (AC) Published paper [29]

Found (TY) Proposed method

Found (TY) Published paper [30]

Found (TY) Proposed method

Found (TY) Published paper [31]

CAP tablet

–

– 10.00 – 25.00 – –

– – – 25.00 – –

– – – 25.00 – –

4.55 ± 0.65 14.93 ± 0.73 bLOD 9.73 ± 0.55 – –

5.01 ± 0.73 15.03 ± 0.85 bLOD 10.05 ± 0.67 – –

– – bLOD 25.76 ± 0.83 10.07 ± 0.78 –

– – bLOD 24.67 ± 0.93 9.81 ± 0.45 –

– – bLOD 25.46 ± 0.85 – –

– – bLOD 25.75 ± 0.87 – –

– – bLOD 24.56 ± 0.95 – 4.87 ± 0.33

– – bLOD 25.75 ± 1.04 – 5.21 ± 0.54

Urine 10.00 AC tablet HCTZ tablet

range of 0.8–550.0 μM; 0.0026 μA μM−1 in the range of 5.0–750.0 μM, and 0.0116 μA μM−1 in the range of 10.0–600.0 μM respectively. The detection limits (3σ) were also found to be 9.0 nM for CAP, 0.3 μM for AC, 1.0 μM for TY and 5.0 μM for HCTZ. Table 1 presents comparisons of the results obtained from the NiO/CNTs/DPID/CPE and those from electrochemical methods recently reported for determination of captopril. The proposed sensor showed better dynamic rage, limit of detection or sensitivity compared to previous published papers. Fig. 6 illustrates the SWV results of obtained for a 10.0 μM CAP solution in the presence of different concentration of AC, TY and HCTZ using NiO/CNTs/DPID/CPE as the working electrode. The results reveal no intermolecular interactions between CAP and these species throughout the electro-oxidation. On the other hand, comparisons of the sensitivity of the electrode towards AC (Fig. 6 a), TY (Fig. 6 b) and HCTZ (Fig. 6 c) in mixed samples within the linear dynamic range revealed these values to be very close. The data showed that the electro-oxidation of CAP, AC, TY and HCTZ at the NiO/CNTs/DPID/CPE take place independently and therefore, the simultaneous determination of each species in is possible in the presence of the others. The high concentration of biological and pharmaceutical species like, starch, glucose, alanine, phenyl alanine, vitamin C, glucose, methionine, alanine, fructose, phenyl alanine and etc. in biological fluids may cause interferences to the electrochemical signal of the analytes (i.e. CAP, AC, TY and HCTZ) and in turn the sensitivity of the method. Yet, the tests proved no interferences from such species in the case of the simulations determination of CAP, AC, TY and HCTZ at a surface of the NiO/CNTs/DPID/CPEs. The stability of the NiO/CNTs/DPID/CPEs was also evaluated. To this end the proposed sensors were used for the SWV analysis of CAP, AC, TY and HCTZ solutions before and after being immersed in a PBS solution (pH = 9.0) for 20 days and the results were compared. The comparisons revealed a 1.54% decrease in the oxidation signals which can be used as proof of the good stability of the proposed sensor. On the other hand, the reproducibility of the results was check using seven modified electrodes in SWV analysis of mixed samples of CAP, AC, TY and HCTZ and an RSD of the currents obtained with the different electrodes was found to be 3.1%. To test the accuracy of the results obtained for NiO/CNTs/DPID/CPE as a novel sensor, CAP, AC, TY and HCTZ concentrations were determined in tablet and urine samples using the electrode. A standard addition protocol was used for the measurements of CAP, AC, TY and HCTZ concentrations in the real samples and the results were compared with those obtained through other tests ([1] (for captopril); [29] (for acetaminophen); [30] (for Tyrosine); [31] (for hydrochlorothiazide)). The summary presented in Table 2, confirms that the developed electrode and the method based on using has a good efficiency for the determination of CAP, AC, TY and HCTZ in real samples. 4. Conclusion A novel electrochemical sensor was fabricated for the simultaneous determination of CAP, AC, TY and HCTZ. The electrode was based on NiO/CNTs and DPID for the modification of the CPEs for the first time. The resulting NiO/CNTs/DPID/CPE exhibited an excellent electrocatalytic activity for the simultaneous detection of CAP, AC, TY and HCTZ with

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