Highly selective and sensitive differential pulse voltammetric method based on poly(Alizarin)/GCE for determination of cefadroxil in tablet and human urine samples

Adane Kassa; Meareg Amare

doi:10.1016/j.arabjc.2021.103296

View/Download PDF

Buy Reprints

PDF

Translate this page into:

Original article

2021

:14;

202108

doi:

10.1016/j.arabjc.2021.103296

Highly selective and sensitive differential pulse voltammetric method based on poly(Alizarin)/GCE for determination of cefadroxil in tablet and human urine samples

Adane Kassa^{^a}, Meareg Amare^{^b,⁎}

a Department of Chemistry, College of Natural & Computational Sciences, Debre Markos University, Ethiopia

b Department of Chemistry, College of Science, Bahir Dar University, Ethiopia

⁎Corresponding author. amaremeareg@yahoo.com (Meareg Amare)

Received: 2021-5-14, Accepted: 2021-6-24,

Disclaimer:
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.

Abstract

Cefadroxil, which belongs to the first-generation cephalosporin class of β-lactam antibiotics, develops bacterial resistance necessitating development of sensitive and selective method for its determination. This paper reports determination of cefadroxil in tablet and human urine samples using poly(alizarin)/GCE. CV and EIS results confirmed deposition of a conductive and electroactive polymer film. Relative to the peak of cefadroxil at the bare electrode, an irreversible oxidative peak at poly(Aliz)/GCE with four folds of current and much reduced potential verified improvement on electrode surface conductivity and effective surface area. DPV current varied linearly with concentration of cefadroxil in the range 1.0 × 10⁻⁷–1.0 × 10⁻⁴ M with LoD, and LoQ of 8.1 × 10⁻⁹, and 2.7 × 10⁻⁸ M, respectively. Detection of 99. ± 3.01 and 99.5 ± 2.03% cefadroxil of the 10.0 and 20.0 µM nominal tablet samples, respectively showed agreement between the detected amount and tablet label. Spike recovery in the range 99.5–100.5% in tablet and human urine samples and interference recovery results in the presence of selected potential interferents in tablet sample with percent error of 0.0–4.9% validated the applicability of the method for determination of cefadroxil in real samples. Compared with previously reported works on cefadroxil determination, relatively wider linear range and extremely low limit of detection of the present method along with its excellent accuracy and selectivity make the method an outstanding candidate for determination of cefadroxil in real samples.

Keywords

Alizarin

β-lactam

Cefadroxil

Cephalexin

Cephalosporin

Cloxacillin

Show Related Articles from PubMed

1 Introduction

Cephalosporins are group of antibiotics containing the dihydrothiazine ring fused with β-lactam ring (Wang et al., 2019). β-lactam class of antibiotics characterized by having the β-lactam ring in their structure are among the most important classes of antibacterial agents (Shetti et al., 2009). Overuse of antibiotics may lead to environmental contamination, allergies and resistance to broad-spectrum antibacterial drugs, with significant health and economic impact (Arias and Murray, 2009; Kirankumar et al. 2020; Lofrano et al., 2016 ). World Health Organization surveillance campaign on the status of antibiotic resistance demonstrated cephalosporins to be among the most common drugs that have developed bacterial resistance (Arias and Murray, 2009; Carlet et al., 2014). Despite the high level of clinical success, serious mechanisms of resistance have emerged which demand high dose therapy and new pharmacokinetic combination (Wang et al., 2019; Kirankumar et al., 2020).

Cefadroxil (CFL), (6R,7R)-7-[[(2R)-2-amino-2-(4-hydroxyphenyl)acetyl]amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid), which belongs to the first-generation cephalosporin class, is a semi-synthetic broad-spectrum antibiotic orally administered against infections caused by S. pneumoniae, S. aureus, S. pyogenes, and E. coli gram positive and gram negative bacteria (Kirankumar et al., 2020).

Common deleterious drug reactions concomitant of use of cefadroxil (Scheme 1) includes stomach pain, nausea, vomiting, diarrhea, joint pain, feeling restless or hyperactive, unpleasant taste, skin rash, and vaginal itching (Arias and Murray, 2009; Kirankumar et al., 2020). One of the most current health challenges for professionals in the area being antibacterial resistance (Arias and Murray, 2009), development of a rapid, selective, sensitive, and stable method for detection of CFL at its trace level in different matrices is thus crucial.

Spectrophotometric (Kirankumar et al., 2020; Marco et al., 2019; Shantier et al., 2011 ), chromatographic (Rahim et al., 2015; Rao et al., 2014), and LC/MS (Nagarajan et al., 2013) are among the techniques reported for determination of CFL. These techniques however need tedious sample preparation, expensive instrumentation, and are non-eco-friendly (Laina and Girish, 2013; Sanz et al., 2019). In contrast to the conventional techniques, electrochemical techniques including voltammetry are accurate, reproducible, fast, environmentally friendly, and often enable selective determination of various chemical species (Laina and Girish, 2013; Sanz et al., 2019) .

While innertness of carbon based electrodes over a wide potential window makes them excellent candidate transducers in voltammetric measurements, impaired sensitivity and reproducibility due to passivation from polishing materials and products of electrochemical reactions (Hatamie et al., 2015; Yadav et al., 2013) necessitated surface modification. Chemical modifying agents such as carbon nanomaterials (Amare, 2019; Bukkitgar et al., 2020; Ghica et al., 2009 ), metal nanoparticles (Amare et al., 2020; Yadav et al., 2013), polymers (Amare and Admassie, 2020; Peng et al., 2009; Shetti et al., 2020 ), sarfactants (Pushpanjali et al., 2019; Raril and Manjunatha, 2020) and biological components (Jarosz-Wilkołazka et al., 2005) showed control of the physicochemical nature of the electrode/solution interface.

Only limited attempts are reported on voltammetric determination of CFL using modified electrodes (Atif et al., 2020; Sanz et al., 2020). To date, no electrochemical method using poly(1,2-dihydroxyanthraquinone) modified glassy carbon electrode (Poly(Aliz)/GCE), an electrode fabricated easily from an available material, has been reported for determination of CFL. Hence, this work describes differential pulse voltammetric determination of CFL in tablet and human urine samples using poly(Alz)/GCE.

2 Experimetal part

2.1

2.1 Chemicals and apparatus

Analytical grade cefadroxil monohydrate (≥99.0%, Sigma Alderich), K₃[Fe(CN)₆] and K₄[Fe(CN)₆] (98.0%, BDH laboratories supplies, England), KCl (99.5%, Blulux laboratories (p) Ltd), Na₂HPO₄ and NaH₂PO₄ (≥98%, Blulux laboratories (p) Ltd), HCl (37%, Fisher Scientific), NaOH (Extra pure, Lab Tech Chemicals), and alizarin (≥99.7%, Blulux laboratories (p) Ltd) were among the chemicals used.

CHI 760E potentiostat (Austin, Texas, USA), pH meter (AD8000, Romania), refrigerator (Lec refrigeration PLC, England), deionizer (Evoqua water technologies) and electronic balance (Nimbus, ADAM equipment, USA) were also among the instruments/apparatus used.

2.2

2.2 Procedure

2.2.1

2.2.1 Preparation of standard cefadroxil solution

Cefadroxil standard stock solution of 5.0 mM in 100 mL volumetric flask was prepared by dissolving 182.7 mg of monohydrated CFL in deionized water. Working CFL solutions in 0.1 M phosphate buffer solution (PBS) of the appropriate pH were prepared from the stock solution by serial dilution.

2.2.2

2.2.2 Preparation of real samples

2.2.2.1

2.2.2.1 Tablet

Five randomly selected DROX (India) brand tablets labeled as 500 mg CFL/tablet, each with average mass of 572.1 mg, were ground and homogenized using mortar and pastel. Tablet stock solution with theoretical concentration of 2.0 mM CFL was prepared by transfering exactly 41.9 mg powder portion to a 50 mL volumetric flask and fill up to the mark with deionized water. Working solutions of nominal concentrations 10.0 and 20.0 µM in pH 6.0 PBS were then prepared from a 0.1 mM intermdiate tablet solution and kept in a refrigerator until analysis. Tablet samples of 20.0 µM nominal CFL concentration, spiked with various concentrations of standard CFL (0, 5.0, 10.0, 20.0, and 40.0 µM), were also prepared for spike recovery and interferent recovery analysis following the same procedure.

2.2.2.1.1

2.2.2.1.1 Human urine

Fresh human urine sample collected from a volunteer in the laboratory was centrifuged at 4000 rpm for 10.0 min. A 0.5 mL of the supernatant portion was transferred to a 25 mL volumetric flask and filled upto the mark with pH 6.0 PBS. Urine samples spiked with various concentrations of standard CFL (0, 20, and 40 µM CFL) were prepared for spike recovery analysis following the same procedure.

2.2.3

2.2.3 Preparation of poly(Alz)/GCE

Poly(Alz)/GCE was prepared following the reported electropolymerization procedure (Dawit et al., 2020) with substantial modification. Briefly: Polymer film of alizarin was deposited on surface of well-cleaned GCE in pH 7.0 PBS containing 1.0 mM Alz scanned between −1.2 and +1.8 V for 15 cycles at a scan rate of 100 mV s⁻¹. The poly(Alz)/GCE was rinsed with distilled water and stabilized in 0.5 M H₂SO₄ between −0.8 and +0.8 V until a steady voltammogram was obtained.

2.3

2.3 Electrochemical measurement

A conventional three electrode system with silver/silver chloride (3.0 M KCl) as reference, platinum coil as counter, and bare or poly(Alz) modified GCE as working electrode was used. While electrochemical impedance spectroscopy and cyclic voltammetry using Fe(CN)₆^3−/4− as a probe were used to characterize the surface of the modified electrode, cyclic voltammetry was further employed to evaluate the electrochemical behavior of CFL at the surface of the poly(Alz)/GCE thereby studying selected associated kinetic parameters. Finally, a differential pulse voltammetric method using the modified electrode was developed for quantitative determination of CFL in tablet and human urine samples.

3 Results and discussion

3.1

3.1 Preparation of poly(Alz)/GCE

In the attempt to deposite poly(Alz) film on the surface of GCE, the potential scan range, and monomer pH were optimized using CFL as a probe.

Fig. 1 presents the response of poly(Alz)/GCEs, prepared by scanning the potential between −0.2 and +1.8 V (Dawit et al., 2020), and a new potential window between −1.2 and +1.8 V for CFL. As can be seen from the figure, the oxidative peak current response for CFL at the polymer film deposited using a wider potential window (curve b of the inset) is relatively higher than the current response for the same at the polymer film obtained using the narrower window (curve a of the inset). The observed peak current enhancement for CFL with increasing potential window might be attributed to deposition of a thicker polymer film due to favorable potential and hence the potential window −1.2 to +1.8 V was selected.

CVs of pH 7.0 PBS containing no CFL (a & b), and 1.0 mM CFL (c & d) at poly(Alz)/GCE synthesized by scanning the potential of GCE in pH 7.0 PBS containing 1.0 mM Alz between −0.2 & +1.8 V (a & c) and −1.2 & +1.8 V (b & d) at a scan rate of 100 mV s−1 for 15 cycles. Inset: background corrected voltammograms of 1.0 mM CFL at poly(Alz)/GCE synthesized in a potential window of (a) −0.2 & +1.8 V, and (b) −1.2 & +1.8 V.

To optimize the pH of the monomer solution, the responses of poly(Alz)/GCE synthesized from 1.0 mM Alz in PBS of various pHs (4.0, 7.0, and 9.0) all by scanning between −1.2 and +1.8 V were compared (Fig. 2). The poly(Alz)/GCE fabricated from the monomer in pH 7.0 PBS showed the highest catalytic effect towards oxidation of CFL in terms of both the current enhancement (Inset A), and overpotential reduction (Inset B).

CVs of pH 7.0 PBS containing no (a-c) and 1.0 mM CFL (d-f) at poly(Alz)/GCE fabricated from 1.0 mM Alz monomer in PBS of various pHs (a-f: 4.0, 9.0, and 7.0, respectively). Inset: plot of (A) background corrected peak current, and (B) peak potential of CFL versus pH of monomer solution.

Therefore, poly(Alz) /GCE synthesized from alizarin monomer in pH 7.0 PBS scanned between −1.2 and +1.8 V for 15 cycles (Fig. 3) was selected for determination of CFL in tablet and human urine samples.

CVs of 1.0 mM Alz in pH 7.0 PBS at GCE scanned between −1.2 & +1.8 V at a scan rate of 100 mV s−1 for 15 cycles. Inset: CVs of (a) bare GCE, and (b) stabilized poly(Alz)/GCE both between −0.8 and +0.8 V at 100 mV s−1 in 0.5 M H2SO4.

Observed increase of current intensity with increasing scan cycles (Fig. 3) for both the anodic (a) and cathodic (a’) peaks centered at about +1352 and −463 mV, respectively confirmed polymer film deposition at the electrode surface. In contrast to the broad reductive peak (≈ −600 mV) at bare GCE (curve a of inset) assigned for reduction of molecular oxygen, appearance of multiple oxidative and reductive peaks at poly(Alz)/GCE in the same solution (curve b of inset) further confirmed the deposition of an electroactive polymer film on the electrode surface.

3.2

3.2 Characterization of the surface of modified electrode

3.2.1

3.2.1 Electrochemical impedance spectroscopy

Electrochemical impedance spectroscopic (EIS) technique as a tool to characterize the surface of the electrode was used to investigate the conductivity of the electrode surface.Fig. 4 presents Nyquist plots of the bare GCE (curve a) and poly(Alz)/GCE (curve b) in pH 7.0 PBS containing Fe(CN)₆^3−/4− as a probe.

Nyquist plot for bare GCE (a) and poly(Alz)/GCE (b) in pH 7.0 PBS containing equi-molar (10.0 mM) mixture of Fe(CN)63−/4−, and 0.1 M KCl recorded at frequency range 0.01–100,000 Hz, amplitude 0.01 V, and potential 0.23 V. Inset: zoomed part of curve b.

Both the bare GCE and poly(Alz)/GCE revealed semi-circles of different diameter at high frequency region and a line at about 45° at low frequency region attributed to diffusion of the probe from the bulk solution towards electrode-solution interface. In contrast to the unmodified electrode (curve a), the poly(Alz)/GCE (curve b) possessed a semi-circle with very small diameter (inset) indicating that the surface of the electrode is modified with an electroactive polymer film that improved the conductivity of the electrode surface.

Table 1 presents values for selected circuit elements (R_ct, R_s, and C_dl) for the two electrodes calculated using eq. (1), where C_dI is double layer capacitance, f is frequency corresponding to the maximum value of the imaginary resistance, R_ct is charge transfer resistance.

(1)

C_{dl} = \frac{1}{2 π R_{ct} f}

Table 1 Values of selected circuit elements for the studied electrodes.

Electrode	R_s/Ω cm²	R_ct/Ω cm²	C_dl/F	Frequency/Hz
GCE	21.8	5427.0	1.2 × 10⁻⁵	2.5
poly(Alz)	21.8	105.1	1.2 × 10⁻³	1.3

The lower R_ct value (105.1 Ω) of the poly(Alz)/GCE than the unmodified electrode (5427.0 Ω), which confirms modification of the electrode surface by a more conductive material, might be explained by a reduced overpotential or improved reversibility of the probe.

3.2.2

3.2.2 Cyclic voltammetry

Cyclic voltammetry using Fe(CN)₆)^3−/4− as a probe was also used to characterize the surface of the modified electrode.

As can be observed from Fig. 5, pair of characteristic redox peaks of Fe(CN)₆^3−/4− are apparent at both electrodes although with differing peak shape, peak-peak potential separation (ΔE), and peak current. In contrast to a pair of broad redox peaks with ΔE 440 mV, and Ipc/Ipa 1.6 for the probe at the unmodified GCE (curve a), appearance of sharp redox peaks with only ΔE 93 mV, Ipc/Ipa 1.2, and of course about two folds of current enhancement for the probe at the poly(Alz)/GCE showed catalytic property of the modifier towards the probe. While lowering of peak-to-peak potential separation (440 to 93 mV) and improving Ipc/Ipa ratio (1.6 to 1.2) is in agreement with the conductivity results from the EIS study, the observed peak current enhancement may be due to possible increase in effective surface area of the modified electrode.

CVs of (a) GCE, (b) poly(Alz)/GCE in pH 7.0 PBS containing 10.0 mM (Fe(CN)6)3−/4− and 0.1 M KCl at a scan rate of 100 mV s−1.

To investigate the effect of surface modification on the electrode surface area, cyclic voltammograms of Fe(CN)₆^3−/4− at both the unmodified and poly(Alz) modified GCEs (Fig. 6) were recorded at various scan rates. Active surface area for both electrodes was calculated from the slope value of plot of Ipa vs ν^1/2 in the Randles–Sevcik equation Eq. (2) (Bard and Faulkner, 2001).

(2)

Ip = 2.69 χ 10^{5} n^{3 / 2} A D^{1 / 2} v^{1 / 2} C_{o}

where Ip is peak current, n number of electron participated (n = 1), A active surface area of the electrode, D diffusion coefficient of the probe (D = 7.6 × 10⁻⁶ cm s⁻¹), C_o the concentration of the probe (10.0 mM), and ν scan rate. Relative to the effective surface area of the unmodified GCE (0.05 cm²), a threefold effective surface area of poly(Alz)/GCE (0.16 cm²) showed modification of the electrode surface by a conductive polymer film that increased the effective surface area. It can therefore be concluded that the peak current enhancement observed for the probe in Fig. 5 at the poly(Alz)/GCE is due to the improved active surface area of the electrode.

CVs of bare GCE (A), and poly(Alz)/GCE (B) in pH 7.0 PBS containing 10.0 mM Fe(CN)63−/4− and 0.1 M KCl at various scan rates (a–l: 10, 20, 40, 60, 80, 100, 125, 150, 175, 200, 250, and 300 mV s−1, respectively). Inset: plot of oxidative peak current versus square root of scan rate.

3.3

3.3 Cyclic voltammetric investigation of CFL at poly(Aliz)/GCE

3.3.1

3.3.1 Electrochemical behavior of CFL

The electrochemical behavior of CFL in pH 7.0 PBS both at the unmodified and poly(Alz) modified glassy carbon electrodes was investigated (Fig. 7). Appearance of a sharp oxidative peak with fourfold of current at much reduced potential (0.840 V) (curve b of inset) at poly(Alz)/GCE relative to the weak, and broad oxidative peak (≈1.160 V) at bare GCE (curve a of inset) confirmed the catalytic effect of the poly(Alz)/GCE towards oxidation of CFL. The observed peak current enhancement, and overpotential reduction of CFL at the modified electrode could be attributed to the increased effective surface area, and improved surface conductivity results, respectively (Hatefi-Mehrjardi et al., 2014).

CVs of bare (a & b) and poly(Alz)/GCE (c & d) in pH 7.0 PBS containing no (a & c) and 1.0 mM CFL (b & d) at scan rate of 100 mV s−1. Inset: Corrected for blank CVs of (a) bare GCE, and (b) poly(Alz)/GCE.

3.3.2

3.3.2 Effect of scan rate on peak current and peak potential of CFL

Fig. 8A presents cyclic voltammograms of CFL in pH 7.0 PBS at various scan artes. Observed peak potential shift in the positive direction with scan rate (Fig. 8A) confirmed irreversibility of CFL oxidation at poly(Alz)/GCE. In contrast to the determination coefficient (R² 0.98737) for the linear dependence of peak current on scan rate (Fig. 8B), a better value for the dependence of peak current on square root of scan rate (R² = 0.99120) (Fig. 8C) indicated that oxidation of CFL at polymer modified electrode was predominantly diffusion controlled (Tasdemir et al., 2012). Slope of 0.52 for the graph log(Ip) versus log( $ν$ ) (Fig. 8D), which is close to the ideal value 0.50 for completely diffusion controlled reaction, further confirmed the oxidation of CFL at the poly(Alz)/GCE was predominantly diffusion controlled (Tasdemir et al., 2012).

(A) CVs of poly(Alz)/GCE in 1.0 mM CFL (pH 7.0 PBS) at different scan rates (a–k: 20, 40, 60, 80, 100, 125, 150, 175, 200, 250, and 300 mV s−1, respectively), (B) plot of Ip versus ν , (C) plot of Ip versus ν 1 / 2 , and (D) plot of log(Ip) versus log ( ν ).

Kinetic parameters including number of electrons participated, and electron transfer coefficient for the oxidation of CFL at poly(Alz)/GCE were calculated. The value of αn in Eq. (3) for an irreversible oxidation was calculated taking the cyclic voltammogram of CFL in pH 6.0 PBS at scan rate of 100 mV s⁻¹ in Fig. 10 (Bard and Faulkner, 2001):

(3)

E_{p} - E_{1 / 2} = 47.7 / α n

where α is the charge transfer coefficient and n the number of electrons transferred.

Plot of Ep versus ln(scan rate) for the CVs of poly(Alz)/GCE in pH 7.0 PBS containing 1.0 mM CFL recorded in the scan rate range of 20–300 mV s−1.

(A) CVs of 1.0 mM CFL in PBS of different pHs (a-i: 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0, respectively), (B) mean ± SD peak (a) current, and (b) potential versus pHs in the entire pH range.

With E_p and E_1/2 of the voltammogram to be 955, and 862 mV, respectively (Fig. 10), αn was calculated to be 0.51. As α for totally irreversible electrode process is 0.50 (Laviron, 1979), the n value was estimated 1.02 (∼1.0), which is in agreement with the literature (Sanz et al., 2020).

Relationship between E_p and lnν for an irreversible process is governed by Eq. (4) (Bard and Faulkner, 2001; Ribeiro and Schmidt, 2017):

(4)

Ep = E^{°} + \frac{RT}{(1 - α) n F} \{0.780 + ln (\frac{D_{R}^{1 / 2}}{k^{°}}) + ln {[\frac{(1 - α) n F v}{RT}]}^{1 / 2}\}

where E_p peak potential, E^o formal potential, k⁰ (s⁻¹) rate constant, and the other parameters with their usual meanings.

Plot of E_p against lnν for CVs of CFL at various scan rates (Fig. 8A) gives a regression equation of E_p (V) = 0.80 + 0.028lnν (Fig. 9) with a slope of 0.028. At the experimental temperature (25 °C), n(1–α) was 0.461. Considering the one-electron system of CFL at the poly(Alz)/GCE, the α value was estimated 0.54, which is very close to the ideal 0.50 for an irreversible system (Bard and Faulkner, 2001; Sanz et al., 2019).

3.3.3

3.3.3 Effect of pH on peak potential and peak current of CFL

Cyclic voltammograms of poly(Alz)/GCE in PBS of various pHs containing 1.0 mM CFL are presented in Fig. 10A. As potential shift in the negative direction with pH in the entire range (Fig. 10A) is ascribed to proton participation during oxidation of CFL at poly(Alz)/GCE, slope of 0.065 V for plot of oxidative peak potential versus pH (curve b of Fig. 10B) is indication of participation of protons and electrons in a 1:1 ratio (Sanz et al., 2019).

Furthermore, the current of CFL at poly(Alz)/GCE increased with pH from 4.0 to 6.0, which then decreased at values beyond 6.0 (curve a of Fig. 10B) making pH 6.0 the optimum. The trend could be attributed to possible electrostatic interaction between the CFL which has three pKa values (2.48, 7.37, and 9.64) corresponding to the carboxylic acid, amine, and phenol functional groups, respectively (Ribeiro and Schmidt, 2017), and the modifier with pka ≈ 6.94 (Machado et al., 2016). While the observed increasing trend of current with pH from 4.0 to 6.0 may be accounted for the possible attraction between the deprotonated carboxilic acid (pka 2.48) for CFL and protonated alizarine, the decreasing trend beyond pH 6.0 may be for possible repulsion between still deprotonated carboxylic acid of CFL and the alizarine which is being deprotonated.

Based on the calculated kinetic parameters (n and α) and proton:electron ratio (1:1), a reaction meachnism was proposed (scheme 2), which is in agreement with literature (Sanz et al., 2020). From the instability of the radical reaction product perspectives, the authors further propose dimerization of the radical oxidation products.

Proposed irreversible oxidative reaction mechanism for CFL.

3.4

3.4 Amperometric studies of CFL at poly(Alz)/GCE

With the intention to determine the diffusion coefficient (D) of CFL, an amperometric measurements were recorded (Fig. 11) at an applied potential of +1000 mV vs. Ag/AgCl for various concentrations of CFL (60, 80 and 100 μM) in pH 6.0 PBS. The slope of plot of Ip versus (t)⁻^1/2 from Cottrell eq. (5) was used to estimate the diffusion coefficient (D) of CFL towards the poly(Alz)/GCE surface.

(5)

I_{p} = \frac{nFA D^{1 / 2} C *}{{(π t)}^{1 / 2}}

where I_p, n, F, A, D, C* and t represent the peak current (A), number of electrons transfer, Faraday’s constant (C mol⁻¹), area of the electrode (cm²), diffusion coefficient (cm² s⁻¹), initial concentration of CFL (µM) and time (s), respectively. Taking n 1, A 0.16 cm², and others their usual values, the average diffusion coefficient as mean ± RSD calculated from the slope of plot of Ip versus t^−1/2 (D = 6.41 × 10⁻⁵ ± 1.03 × 10⁻⁶) is in agreement with the value reported in literature (Sanz et al., 2019).

Amperommetric i–t curves for various concentrations of CFL (a-c: 60, 80, and 100 µM CFL, respectively) in pH 6.0 PBS at poly (Alz)/GCE. Insets: Plot of Ip versus (t)−1/2 for CFL (A-C: 60, 80, and 100 µM, respectively).

3.5

3.5 Differential pulse voltammetric determination of CFL at poly(Alz)/GCE

The fact that differential pulse voltammetry (DPV) is more powerful to discremenate Faradaic from the non-Faradaic current and hence higher sensitivity, better resolution, and lower detection limit than cyclic voltammetry (Fiedler and Scholz, 2010; Sanz et al., 2020), DPV was employed for quantitative determination of CFL in tablet and human urine samples. Fig. 12 presents DPVs of 1.0 mM CFL in pH 6.0 PBS at unmodified GCE and poly(Alz)/GCE. An oxidative peak at much reduced potential with fivefold current enhancement at poly(Alz)/GCE (curve b of inset) (26.9 µA, & 865 mV) than at the unmodified GCE (5.3 µA, & 951 mV) (curve a of inset) signified the catalytic effect of the modifier towards the oxidation of CFL.

DPVs of bare GCE (a & b) and poly(Alz)/GCE (c & d) in pH 6.0 PBS containing no (a & c) and 1.0 mM CFL (b & d) at potential increment, and amplitude of 4 and 50 mV, respectively. Inset: corrected for background DPVs of CFL at a) bare GCE, and b) poly(Alz)/GCE.

3.5.1

3.5.1 Optimization of DPV parameters

Fig. 13 presents the differential pulse voltammogams at different step potentials (A) and pulse amplitudes (B). As a compromise between the increase in Faradaic and Non-Faradaic currents with increasing step potential and amplitude, 8 and 75 mV, respectively were taken as the optimum values in this study.

DPVs of poly(Alz)/GCE in 1.0 mM CFL (pH 6.0 PBS) at (A) various step potentials (a-e: 2, 4, 6, 8, and 10 mV, respectively) and amplitude of 50 mV, and (B) various pulse amplitudes (a-f: 10, 25, 50, 75, 100, and 125 mV, respectively) and 8 mV step potential. Insert: plot of Ip versus (A) step potential and (B) pulse amplitude.

3.5.2

3.5.2 Calibration curve of CFL at poly(Alz)/GCE

Under the optimized solution and method parameters, representative DPVs of varying concentrations of CFL are presented in Fig. 14. The average current response of poly(Alz)/GCE for CFL (n = 3) increased linearly with concentration in the range 1.0 × 10⁻⁷–1.0 × 10⁻⁴ M with a linear regression equation, determination coefficient (R²), LoD (3 s/m for n 7) and LoQ (10 s/m) of Ip/μA = −1.3 ± 0.034–0.14C ± 0.001/μM, 0.99951, 8.1 × 10⁻⁹ M, and 2.7 × 10⁻⁸ M, respectively (inset of Fig. 14). RSD values below 3.2%, associated with triplicate current measurement throughout the studied concentration range showed the precision of the method.

Representative background corrected DPVs of poly(Alz)/GCE in pH 6.0 PBS containing various concentrations of CFL (a-j: 0.1, 0.5, 1.0, 5.0, 10.0, 20.0, 40.0, 60.0, 80.0, and 100.0 µM, respectively) at optimum method parameters. Inset: plot of average peak current (mean±%RSD) versus concentration of CFL.

3.5.3

3.5.3 DPV determination of CFL in real samples

3.5.3.1

3.5.3.1 Tablet sample

The level of CFL in Drox (Indian) brand CFL tablet sample was determined using the developed method and the detected amount was further compared with the nominal CFL content of the tablet powder portion according to the tablet label.

Fig. 15 presents DPVs of tablet samples with nominal CFL of 10.0 and 20.0 μM (curve a & b, respectively). The detected CFL content in the tablet samples as calculated from the calibration regression equation was compared with the nominal CFL content (Table 2).

Background corrected DPVs of poly(Alz)/GCE in pH 6.0 PBS containing (a) 10.0, and (c) 20.0 µM nominal CFL in tablet samples.

Table 2 Summary of theoretical CFL content in tablet samples, detected CFL content, and percent detected as compared to the theoretical value for both tablet samples.

Labeled CFL (mg/tablet)	Theoretical CFL in tablet sample (µM)	Detected CFL in sample		Detected CFL %^b
Labeled CFL (mg/tablet)	Theoretical CFL in tablet sample (µM)	(µM)^a	(mg/tablet)	Detected CFL %^b
500	10.0	9.9 ± 0.03	495.0	99.0 ± 3.01
500	20.0	19.9 ± 0.02	497.5	99.5 ± 2.03

a Detected mean CFL ± %RSD, ^bDetected % CFL ± %RSD.

As can be seen from the table, detected CFL content in the range 99.0–99.5% of what is theoreticall expected with %RSD value below 3.0% showed the closeness of the detected CFL with the nominal value and even precision of the method.

3.5.3.1.1

3.5.3.1.1 Human urine sample

Fig. 16a presents corrected for blank DPV for a human urine samples prepared following the procedure described under the experimental part. While absence of a peak at the characteristic potential of CFL indicates absence of CFL in the analyzed human urine sample, appearance of a peak at a potential away from the characteristic potential for CFL tells presence of a non-assignable electroactive substance in the urine sample. The selectivity of the method for CFL in human urine in the presence of the non-assignable substance was further examined by spike recovery test.

Background subtracted DPVs of poly(Alz)/GCE in pH 6.0 PBS containing A) unspiked urine sample, B) A + 20.0 µM standard CFL, and C) A + 40.0 µM standard CFL.

3.6

3.6 Method validation

Recovery of spiked standards, interference studies, precicion, stability and LoD were among the parameters used to validate the developed method for its applicability for determination of CFL in real samples including human urine and tablet samples.

3.6.1

3.6.1 Spike recovery studies

To check the accuracy of the method, recovery studies for spiked CFL in human urine and tablet sample solutions was conducted.

3.6.1.1

3.6.1.1 Human urine sample

Recovery of CFL in spiked human urine sample was carried out by spiking the human urine sample analyzed under 3.5.3.2 with 20.0 and 40.0 µM CFL standard solutions (Fig. 16). The urine samples (curves A-C) revealed a peak centered at about 700 mV (peak a) with exactly constant current intensity regardless of level of spiked CFL confirming that the peak is not for CFL. On the other hand, appearance of a new peak (peak b) at the characteristic potential of CFL (≈ 800 mV) whose current intensity increased with amount of spiked CFL in the urine samples (curves B & C) substantiated the peak in the unspiked urine is not for CFL. Spike recovery of 99.5% for 20.0 and 100.5% for 40.0 µM (Table 3) CFL in human urine samples showed accuracy of the method.

Table 3 Recovery results of 20.0 and 40.0 µM CFL in spiked human urine samples.

Sample	Added (µM)	Found (µM)^c	Recovery (%)^d
1	20.0	19.9 ± 0.02	99.5 ± 2.31
2	40.0	40.2 ± 0.02	100.5 ± 1.52

c Detected mean CFL ± %RSD, ^d % Recovery CFL ± %RSD.

3.6.1.2

3.6.1.2 Tablet sample

Five similarly prepared tablet samples were spiked with four different concentrations (samples 1–5: 0, 5.0, 10.0, 20.0, and 40.0 µM) of standard CFL. The DPVs for the unspiked (curve a) and spiked (curves b-e) CFL tablet sample solutions are presented (Fig. S-1). Recovery results in the range 99.6–100.5% (Table 4) for spiked standards in tablet samples still confirmed the accuracy of the method.

Table 4 Summary of spike recovery results of 5.0 10.0, 20.0, and 40.0 μM CFL from tablet solutions containing 19.9 ± 0.02 µM CFL tablet samples.

Tablet sample	Spiked CFL (µM)	Expected CFL (µM)	Detected CFL (mean ± RSD) (µM)	Recovery (%)
1	–––	19.9	19.9 ± 0.02	–––
2	5.00	24.9	24.8 ± 0.02	99.6
3	10.00	29.9	29.8 ± 0.03	99.7
4	20.00	39.9	39.9 ± 0.02	100.0
5	40.00	59.9	60.2 ± 0.03	100.5

3.6.2

3.6.2 Interference study

Selectivity of the proposed method for CFL in the presence of various foreign species was investigated. In this study, drugs which could be present in the CFL tablet or have structural similarities with CFL, otherwise administrated together with CFL (cefalexin, ampicillin, cloxacillin, and ascorbic acid) were selected. The effect of each interferent was investigated at its various concentrations (Fig. S-2). As can be seen from Table S-3, the presence of cloxacillin (CLN), cephalexin (CEF), ampicillin (AMP), and ascorbic acid (AA) at their various levels in tablet sample containing fixed amount of CFL resulted in random errors that are all under the tolerance limit (±5%) showing the selectivity of the method.

3.6.3

3.6.3 Stability study

The %RSD for quintuplicate measurements of the current for CFL at poly(Alz)/GCE recorded at an interval of two hrs in a day (Fig. S-4)) and for similar five measurements recorded at an interval of four days in twenty days time (Fig. S-5) were only 2.1%, and 2.9%, respectively. An error below 3.0% for multiple measurements of the current of a fixed concentration of CFL revealed the stability of the polymer film.

Therefore, excellent spike recovery results, interference recovery results, and stability added with wide linear range and low LoD results validated the applicability of the developed method for determination of CFL in real samples with complex matrix like tablet and human urine samples.

3.7

3.7 Performance evaluation of the present method

The performance of the present method based on poly(Alz)/GCE was compared with recently reported methods in terms of the linear range, limit of detection, and cost/availability of the surface modifier used.

The present method based on poly(Alz)/GCE showed the widest linear range with the lowest LoD than the previously reported methods (Table 5). Therefore, the reported method using glassy carbon electrode as a substrate and easily synthesized poly(alizarin) film from an available alizarine monomer as modifier showed superior performance over those which used expensive electrode modifiers.

Table 5 Performance of the present method compared with previously reported works.

Substrate	Modifier	Method	Dynamic range (µM)	LoD (µM)	Ref.
GCE	AuNP/MWCNT	Amperometry	2.0–10.0	0.22	(Sanz et al., 2020)
GCE	nano-Ag-APME	SW-AdSV	0.033–0.304 & 10–70	0.01 & 0.03	(Atif et al., 2020)
GCE	Poly(Alz)	DPV	0.1–100	0.0081	This work

4 Conclusions

EIS and CV results of Fe(CN)₆^3−/4− at poly(Alz)/GCE fabricated under optimized electropolymerization potential window and pH of the monomer solution confirmed deposition of a conductive electroactive polymer film on the surface of glassy carbon electrode. In contrast to the response of bare GCE for CFL, appearance of an oxidative peak with four-fivefold current at much reduced potential at poly(Alz)/GCE was accounted for the improved conductivity of the polymer film and increased effective electrode surface area. Study of effects of solution pH and scan rate on both the peak current and peak potential of CFL at poly(Alz)/GCE revealed predominantly diffusion controlled irreversible oxidation reaction mechanism of CFL that involves protons and electrons in a 1:1 ratio. The current response of poly(Alz)/GCE for CFL varied linear with concentration in the range 1.0 × 10⁻⁷–1.0 × 10⁻⁴ M with LoD of 8.1 × 10⁻⁹ M. The developed method based on poly(Alz)/GCE was applied for determination of CFL in real samples including tablet formulation and human urine samples. Closeness of the detected CFL content in tablet formulation with the nominal value, %RSD values under 3% for all replicate intra-day, and inter-day replicate measurements and hence stability of the modifier, low method limit of detection, and wide linear dynamic range all validated the present method for determination of CFL in tablet and urine samples. In contrast to voltammetric methods previously reported for determination of CFL, the present method showed excellent performance explained by its low limit of detection, wide linear dynamic range, and availability of the surface modifier. Thus, the developed method can be applied successfully in the analysis of CFL in drug, and urine samples.

Acknowledgements

The authors would like to thank the Department of Chemistry, Bahir Dar University for providing us working laboratory to work in. The authors also thank Addis Pharmaceutical factory (APF), Ethiopia Food and Drug Administration Authority (EFDA), and Ethiopian Pharmaceuticals Manufacturing factory (EPHARM) for supplying us with standard chemicals.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

Amare M., . Electrochemical characterization of iron (III) dopped zeolite-graphite composite modified glassy carbon electrode and its application for AdASSWV determination of uric acid in human urine. Int. J. Anal. Chem.. 2019;2019:1-10.
[CrossRef] [Google Scholar]
Amare M., Admassie S., . Potentiodynamic fabrication and characterization of poly(4-amino-3-hydroxynaphthalene sulfonic acid) modified glassy carbon electrode. J. Mater. Res. Technol.. 2020;9(5):11484-11496.
[CrossRef] [Google Scholar]
Amare M., Worku A., Kassa A., Hilluf W., . Green synthesized silver nanoparticle modified carbon paste electrode for SWAS voltammetric simultaneous determination of Cd(II) and Pb(II) in Bahir Dar Textile discharged effluent. Heliyon. 2020;6(7):e04401
[CrossRef] [Google Scholar]
Arias C.A., Murray B.E., . Antibiotic-resistant bugs in the 21st century—a clinical super-challenge. N. Engl. J. Med.. 2009;360(5):439-443.
[CrossRef] [Google Scholar]
Atif S., Baig J.A., Afridi H.I., Kazi T.G., Waris M., . Novel nontoxic electrochemical method for the detection of cefadroxil in pharmaceutical formulations and biological samples. Microchem. J.. 2020;154:104574
[CrossRef] [Google Scholar]
Bard A.J., Faulkner L.R., . Electrochemical Methods: Fundamentals and applications (second ed.). New York: John Willey & Sons; 2001.
Bukkitgar S.D., Shetti N.P., Reddy K.R., Saleh T.A., Tejraj M., . Ultrasonication and electrochemically-assisted synthesis of reduced graphene oxide nanosheets for electrochemical sensor applications. FlatChem. 2020;23:100183
[CrossRef] [Google Scholar]
Carlet J., Pulcini C., Piddock L.J., . Antibiotic resistance: a geopolitical issue. Clin. Microbiol. Infect.. 2014;20(10):949-953.
[CrossRef] [Google Scholar]
Dawit M., Turbale M., Moges A., Amare M., . Poly (alizarin red S) modified glassy carbon electrode for square wave adsorptive stripping voltammetric determination of metronidazole in tablet formulation. Plos One. 2020;15(12):1-17.
[CrossRef] [Google Scholar]
Fiedler D.A., Scholz F., . Electrochemical studies of solid compounds and materials. In: Electroanalytical Methods. Berlin, Heidelberg: Springer; 2010.
[CrossRef] [Google Scholar]
Ghica M.E., Pauliukaite R., Fatibello-Filho O., Brett C.M., . Application of functionalised carbon nanotubes immobilised into chitosan films in amperometric enzyme biosensors. Sens. Actuators B: Chem.. 2009;142(1):308-315.
[CrossRef] [Google Scholar]
Hatamie A., Echresh A., Zargar B., Nur O., Willander M., . Fabrication and characterization of highly-ordered zinc oxide nanorods on gold/glass electrode, and its application as a voltammetric sensor. Electrochim. Acta. 2015;174:1261-1267.
[CrossRef] [Google Scholar]
Hatefi-Mehrjardi A., Ghaemi N., Karimi M.A., Ghasemi M., Islami-Ramchahi S., . Poly-(alizarin red s)-modified glassy carbon electrode for simultaneous electrochemical determination of levodopa, homovanillic acid and ascorbic acid. Electroanalysis. 2014;26(11):2491-2500.
[CrossRef] [Google Scholar]
Jarosz-Wilkołazka A., Ruzgas T., Gorton L., . Amperometric detection of mono-and diphenols at Cerrena unicolor laccase-modified graphite electrode: correlation between sensitivity and substrate structure. Talanta. 2005;66(5):1219-1224.
[CrossRef] [Google Scholar]
Kirankumar S.V., Jose Gnana Babu C., Sowmya H.G., . Validated AUC method for the spectrophotometric estimation of cefadroxil in bulk and tablet dosage form. Int. J. Chem. Pharm. Anal.. 2020;7(6):226-230.
[Google Scholar]
Laina L., Girish K., . Voltammetric sensors for the determination of pharmaceuticals. Cochin University of Science and Technology; 2013. Doctoral dissertation
Laviron E., . General expression of the linear potential sweep voltammogram in the case of diffusionless electrochemical systems. J. Electroanal. Chem. Interf. Electrochem.. 1979;101(1):19-28.
[CrossRef] [Google Scholar]
Lofrano G., Libralato G., Adinolfi R., Siciliano A., Iannece P., Guida M., Giugnic M., Ghirardinid A.V., Carotenuto M., . Photocatalytic degradation of the antibiotic chloramphenicol and effluent toxicity effects. Ecotoxicol. Environ. Saf.. 2016;123:65-71.
[CrossRef] [Google Scholar]
Machado F.M., Carmalin S.A., Lima E.C., Dias S.L., Prola L.D., Saucier C., Jauris I.M., Zanella I., Fagan S.B., . Adsorption of alizarin red s dye by carbon nanotubes: an experimental and theoretical investigation. J. Phys. Chem. C. 2016;120(32):18296-18306.
[CrossRef] [Google Scholar]
Marco B., Kogawa A., Salgado H., . New, green and miniaturized analytical method for determination of cefadroxil monohydrate in capsules. Drug Anal. Res.. 2019;3(1):23-28.
[Google Scholar]
Nagarajan J.S.K., Vimal C.S., George R., Dubala A., . Simultaneous pharmacokinetic assessment of cefadroxil and clavulanic acid in human plasma by LC–MS and its application to bioequivalence studies. J. Pharm. Anal.. 2013;3(4):285-291.
[CrossRef] [Google Scholar]
Peng H., Zhang L., Soeller C., Travas-Sejdic J., . Conducting polymers for electrochemical DNA sensing. Biomaterials. 2009;30(11):2132-2148.
[CrossRef] [Google Scholar]
Pushpanjali P.A., Manjunatha J.G., Shreenivas M.T., . The electrochemical resolution of ciprofloxacin, riboflavin and estriol using anionic surfactant and polymer-modified carbon paste electrode. ChemistrySelect. 2019;4(46):13427-13433.
[CrossRef] [Google Scholar]
Rahim N., Naqvi S.B., Shakeel S., Iffat W., Muhammad I.N., . Determination of cefadroxil in tablet/capsule formulations by a validated reverse phase high performance liquid chromatographic method. Pak. J. Pharm. Sci.. 2015;28(4):1345-1349.
[Google Scholar]
Rao K.G., Uma B., Shankar B., Naik B.M., . Development and validation of RP-HPLC method for the estimation of cefadroxil monohydrate in bulk and its tablet dosage form. J. Adv. Pharm. Edu. Res.. 2014;4(1):71-74.
[Google Scholar]
Raril C., Manjunatha G.J., . A simple approach for the electrochemical determination of vanillin at ionic surfactant modified graphene paste electrode. Microchem. J.. 2020;154:104575
[CrossRef] [Google Scholar]
Ribeiro A.R., Schmidt T.C., . Determination of acid dissociation constants (pKa) of cephalosporin antibiotics: computational and experimental approaches. Chemosphere. 2017;169:524-533.
[CrossRef] [Google Scholar]
Sanz C.G., Serrano S.H., Brett C.M., . Electrochemical characterization of cefadroxil β-lactam antibiotic and Cu (II) complex formation. J. Electroanal. Chem.. 2019;844:124-131.
[CrossRef] [Google Scholar]
Sanz C.G., Serrano S.H., Brett C.M., . Electroanalysis of cefadroxil antibiotic at carbon nanotube/gold nanoparticle modified glassy carbon electrodes. ChemElectroChem. 2020;7(9):2151-2158.
[CrossRef] [Google Scholar]
Shantier S.W., Gadkariem E.A., Ibrahim K.E., El-Obeid H.A., . Spectrophotmetric determination of cefadroxil in bulk and dosage form using sodium hydroxide. E-J. Chem.. 2011;8(3):1314-1322.
[CrossRef] [Google Scholar]
Shetti N.P., Hegde R.N., Nandibewoor S.T., . Structural reactivity and thermodynamic analysis on oxidation of ampicillin drug by copper(III) complex in aqueous alkaline medium (stopped-flow technique) J. Mol. Struct.. 2009;930:180-186.
[CrossRef] [Google Scholar]
Shetti N.P., Ilager D., Malode S.J., Monga D., Basu S., Reddy K.R., . Poly(eriochrome black T) modified electrode for electrosensing of methdilazine. Mater. Sci. Semicond. Process.. 2020;120:105261
[CrossRef] [Google Scholar]
Tasdemir I.H., Ece A., Kilic E., . Experimental and theoretical study on the electrochemical behavior of zofenopril and its voltammetric determination. Curr. Pharm. Anal.. 2012;8(4):339-348.
[CrossRef] [Google Scholar]
Wang Q., Wang D., Wang J., Cui Y., Xu H., . Recent progress and novel perspectives of electrochemical sensor for cephalosporins detection. Int. J. Electrochem. Sci.. 2019;14(9):8639-8649.
[CrossRef] [Google Scholar]
Yadav S.K., Agrawal B., Goyal R.N., . AuNPs-poly-DAN modified pyrolytic graphite sensor for the determination of cefpodoxime proxetil in biological fluids. Talanta. 2013;108:30-37.
[CrossRef] [Google Scholar]

Appendix A

Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.arabjc.2021.103296.

Appendix A

Supplementary data

The following are the Supplementary data to this article:

Supplementary data 1

Download

Show Sections

[1] Amare M., . Electrochemical characterization of iron (III) dopped zeolite-graphite composite modified glassy carbon electrode and its application for AdASSWV determination of uric acid in human urine. Int. J. Anal. Chem.. 2019;2019:1-10.
[CrossRef] [Google Scholar]

[2] Amare M., Admassie S., . Potentiodynamic fabrication and characterization of poly(4-amino-3-hydroxynaphthalene sulfonic acid) modified glassy carbon electrode. J. Mater. Res. Technol.. 2020;9(5):11484-11496.
[CrossRef] [Google Scholar]

[3] Amare M., Worku A., Kassa A., Hilluf W., . Green synthesized silver nanoparticle modified carbon paste electrode for SWAS voltammetric simultaneous determination of Cd(II) and Pb(II) in Bahir Dar Textile discharged effluent. Heliyon. 2020;6(7):e04401
[CrossRef] [Google Scholar]

[4] Arias C.A., Murray B.E., . Antibiotic-resistant bugs in the 21st century—a clinical super-challenge. N. Engl. J. Med.. 2009;360(5):439-443.
[CrossRef] [Google Scholar]

[5] Atif S., Baig J.A., Afridi H.I., Kazi T.G., Waris M., . Novel nontoxic electrochemical method for the detection of cefadroxil in pharmaceutical formulations and biological samples. Microchem. J.. 2020;154:104574
[CrossRef] [Google Scholar]

[6] Bard A.J., Faulkner L.R., . Electrochemical Methods: Fundamentals and applications (second ed.). New York: John Willey & Sons; 2001.

[7] Bukkitgar S.D., Shetti N.P., Reddy K.R., Saleh T.A., Tejraj M., . Ultrasonication and electrochemically-assisted synthesis of reduced graphene oxide nanosheets for electrochemical sensor applications. FlatChem. 2020;23:100183
[CrossRef] [Google Scholar]

[8] Carlet J., Pulcini C., Piddock L.J., . Antibiotic resistance: a geopolitical issue. Clin. Microbiol. Infect.. 2014;20(10):949-953.
[CrossRef] [Google Scholar]

[9] Dawit M., Turbale M., Moges A., Amare M., . Poly (alizarin red S) modified glassy carbon electrode for square wave adsorptive stripping voltammetric determination of metronidazole in tablet formulation. Plos One. 2020;15(12):1-17.
[CrossRef] [Google Scholar]

[10] Fiedler D.A., Scholz F., . Electrochemical studies of solid compounds and materials. In: Electroanalytical Methods. Berlin, Heidelberg: Springer; 2010.
[CrossRef] [Google Scholar]

[11] Ghica M.E., Pauliukaite R., Fatibello-Filho O., Brett C.M., . Application of functionalised carbon nanotubes immobilised into chitosan films in amperometric enzyme biosensors. Sens. Actuators B: Chem.. 2009;142(1):308-315.
[CrossRef] [Google Scholar]

[12] Hatamie A., Echresh A., Zargar B., Nur O., Willander M., . Fabrication and characterization of highly-ordered zinc oxide nanorods on gold/glass electrode, and its application as a voltammetric sensor. Electrochim. Acta. 2015;174:1261-1267.
[CrossRef] [Google Scholar]

[13] Hatefi-Mehrjardi A., Ghaemi N., Karimi M.A., Ghasemi M., Islami-Ramchahi S., . Poly-(alizarin red s)-modified glassy carbon electrode for simultaneous electrochemical determination of levodopa, homovanillic acid and ascorbic acid. Electroanalysis. 2014;26(11):2491-2500.
[CrossRef] [Google Scholar]

[14] Jarosz-Wilkołazka A., Ruzgas T., Gorton L., . Amperometric detection of mono-and diphenols at Cerrena unicolor laccase-modified graphite electrode: correlation between sensitivity and substrate structure. Talanta. 2005;66(5):1219-1224.
[CrossRef] [Google Scholar]

[15] Kirankumar S.V., Jose Gnana Babu C., Sowmya H.G., . Validated AUC method for the spectrophotometric estimation of cefadroxil in bulk and tablet dosage form. Int. J. Chem. Pharm. Anal.. 2020;7(6):226-230.
[Google Scholar]

[16] Laina L., Girish K., . Voltammetric sensors for the determination of pharmaceuticals. Cochin University of Science and Technology; 2013. Doctoral dissertation

[17] Laviron E., . General expression of the linear potential sweep voltammogram in the case of diffusionless electrochemical systems. J. Electroanal. Chem. Interf. Electrochem.. 1979;101(1):19-28.
[CrossRef] [Google Scholar]

[18] Lofrano G., Libralato G., Adinolfi R., Siciliano A., Iannece P., Guida M., Giugnic M., Ghirardinid A.V., Carotenuto M., . Photocatalytic degradation of the antibiotic chloramphenicol and effluent toxicity effects. Ecotoxicol. Environ. Saf.. 2016;123:65-71.
[CrossRef] [Google Scholar]

[19] Machado F.M., Carmalin S.A., Lima E.C., Dias S.L., Prola L.D., Saucier C., Jauris I.M., Zanella I., Fagan S.B., . Adsorption of alizarin red s dye by carbon nanotubes: an experimental and theoretical investigation. J. Phys. Chem. C. 2016;120(32):18296-18306.
[CrossRef] [Google Scholar]

[20] Marco B., Kogawa A., Salgado H., . New, green and miniaturized analytical method for determination of cefadroxil monohydrate in capsules. Drug Anal. Res.. 2019;3(1):23-28.
[Google Scholar]

[21] Nagarajan J.S.K., Vimal C.S., George R., Dubala A., . Simultaneous pharmacokinetic assessment of cefadroxil and clavulanic acid in human plasma by LC–MS and its application to bioequivalence studies. J. Pharm. Anal.. 2013;3(4):285-291.
[CrossRef] [Google Scholar]

[22] Peng H., Zhang L., Soeller C., Travas-Sejdic J., . Conducting polymers for electrochemical DNA sensing. Biomaterials. 2009;30(11):2132-2148.
[CrossRef] [Google Scholar]

[23] Pushpanjali P.A., Manjunatha J.G., Shreenivas M.T., . The electrochemical resolution of ciprofloxacin, riboflavin and estriol using anionic surfactant and polymer-modified carbon paste electrode. ChemistrySelect. 2019;4(46):13427-13433.
[CrossRef] [Google Scholar]

[24] Rahim N., Naqvi S.B., Shakeel S., Iffat W., Muhammad I.N., . Determination of cefadroxil in tablet/capsule formulations by a validated reverse phase high performance liquid chromatographic method. Pak. J. Pharm. Sci.. 2015;28(4):1345-1349.
[Google Scholar]

[25] Rao K.G., Uma B., Shankar B., Naik B.M., . Development and validation of RP-HPLC method for the estimation of cefadroxil monohydrate in bulk and its tablet dosage form. J. Adv. Pharm. Edu. Res.. 2014;4(1):71-74.
[Google Scholar]

[26] Raril C., Manjunatha G.J., . A simple approach for the electrochemical determination of vanillin at ionic surfactant modified graphene paste electrode. Microchem. J.. 2020;154:104575
[CrossRef] [Google Scholar]

[27] Ribeiro A.R., Schmidt T.C., . Determination of acid dissociation constants (pKa) of cephalosporin antibiotics: computational and experimental approaches. Chemosphere. 2017;169:524-533.
[CrossRef] [Google Scholar]

[28] Sanz C.G., Serrano S.H., Brett C.M., . Electrochemical characterization of cefadroxil β-lactam antibiotic and Cu (II) complex formation. J. Electroanal. Chem.. 2019;844:124-131.
[CrossRef] [Google Scholar]

[29] Sanz C.G., Serrano S.H., Brett C.M., . Electroanalysis of cefadroxil antibiotic at carbon nanotube/gold nanoparticle modified glassy carbon electrodes. ChemElectroChem. 2020;7(9):2151-2158.
[CrossRef] [Google Scholar]

[30] Shantier S.W., Gadkariem E.A., Ibrahim K.E., El-Obeid H.A., . Spectrophotmetric determination of cefadroxil in bulk and dosage form using sodium hydroxide. E-J. Chem.. 2011;8(3):1314-1322.
[CrossRef] [Google Scholar]

[31] Shetti N.P., Hegde R.N., Nandibewoor S.T., . Structural reactivity and thermodynamic analysis on oxidation of ampicillin drug by copper(III) complex in aqueous alkaline medium (stopped-flow technique) J. Mol. Struct.. 2009;930:180-186.
[CrossRef] [Google Scholar]

[32] Shetti N.P., Ilager D., Malode S.J., Monga D., Basu S., Reddy K.R., . Poly(eriochrome black T) modified electrode for electrosensing of methdilazine. Mater. Sci. Semicond. Process.. 2020;120:105261
[CrossRef] [Google Scholar]

[33] Tasdemir I.H., Ece A., Kilic E., . Experimental and theoretical study on the electrochemical behavior of zofenopril and its voltammetric determination. Curr. Pharm. Anal.. 2012;8(4):339-348.
[CrossRef] [Google Scholar]

[34] Wang Q., Wang D., Wang J., Cui Y., Xu H., . Recent progress and novel perspectives of electrochemical sensor for cephalosporins detection. Int. J. Electrochem. Sci.. 2019;14(9):8639-8649.
[CrossRef] [Google Scholar]

[35] Yadav S.K., Agrawal B., Goyal R.N., . AuNPs-poly-DAN modified pyrolytic graphite sensor for the determination of cefpodoxime proxetil in biological fluids. Talanta. 2013;108:30-37.
[CrossRef] [Google Scholar]

Highly selective and sensitive differential pulse voltammetric method based on poly(Alizarin)/GCE for determination of cefadroxil in tablet and human urine samples

Abstract

Keywords

Alizarin

β-lactam

Cefadroxil

Cephalexin

Cephalosporin

Cloxacillin

1 Introduction

2 Experimetal part

2.1 Chemicals and apparatus

2.2 Procedure

2.2.1 Preparation of standard cefadroxil solution

2.2.2 Preparation of real samples

2.2.2.1 Tablet

2.2.2.1.1 Human urine

2.2.3 Preparation of poly(Alz)/GCE

2.3 Electrochemical measurement

3 Results and discussion

3.1 Preparation of poly(Alz)/GCE

3.2 Characterization of the surface of modified electrode

3.2.1 Electrochemical impedance spectroscopy

3.2.2 Cyclic voltammetry

3.3 Cyclic voltammetric investigation of CFL at poly(Aliz)/GCE

3.3.1 Electrochemical behavior of CFL

3.3.2 Effect of scan rate on peak current and peak potential of CFL

3.3.3 Effect of pH on peak potential and peak current of CFL

3.4 Amperometric studies of CFL at poly(Alz)/GCE

3.5 Differential pulse voltammetric determination of CFL at poly(Alz)/GCE

3.5.1 Optimization of DPV parameters

3.5.2 Calibration curve of CFL at poly(Alz)/GCE

3.5.3 DPV determination of CFL in real samples

3.5.3.1 Tablet sample

3.5.3.1.1 Human urine sample

3.6 Method validation

3.6.1 Spike recovery studies

3.6.1.1 Human urine sample

3.6.1.2 Tablet sample

3.6.2 Interference study

3.6.3 Stability study

3.7 Performance evaluation of the present method

4 Conclusions

Acknowledgements

Declaration of Competing Interest

References

Appendix A

Supplementary data

Appendix A

Supplementary data

Suggested read for related articles: