Elsevier

Electrochimica Acta

Volume 68, 30 April 2012, Pages 227-234
Electrochimica Acta

Simultaneous determination of paracetamol and penicillin V by square-wave voltammetry at a bare boron-doped diamond electrode

https://doi.org/10.1016/j.electacta.2012.02.071Get rights and content

Abstract

A simple, sensitive and selective square-wave voltammetry method for simultaneous determination of paracetamol and penicillin V on a bare (unmodified) boron-doped diamond electrode has been developed. The good potential separation of about 0.35 V between the oxidation peak potentials of both drugs present in mixture was found. It was found by cyclic voltammetry that paracetamol gave quasireversible wave and penicillin V provided irreversible oxidation peak. The effect of supporting electrolyte, pH and scan rate on voltammetric response of both drugs was studied to select the optimum experimental conditions. The optimal conditions for quantitative simultaneous determination were obtained in acetate buffer solution at pH 5.0. The oxidation peak of paracetamol and penicillin V showed a systematic increase in peak currents with increase of their concentration. The calibration curves for the simultaneous determination of paracetamol and penicillin V exhibited the good linear responses within the concentration range from 0.4 to 100 μM for both drugs. The detection limit was established to 0.21 and 0.32 μM for paracetamol and penicillin V, respectively. The method proved the good sensitivity, repeatability (RSD of 1.5 and 2.1% for mixture solution of 10 μM PCM and PEN) and selectivity when influence of interferents commonly existing in human urine was negligible. The practical analytical utility of proposed method was demonstrated by simultaneous determination of paracetamol and penicillin V in human urine samples, with results similar to those obtained using a high-performance liquid chromatography method as an independent method.

Highlights

► Unmodified BDD electrode = sensitive electrochemical sensor for drugs determination. ► No special pretreatment of samples except simple dilution. ► Selective method, common compounds present in urine do not interfere in high excess. ► Simultaneous determination of PAR and PEN has yet not been published in literature.

Introduction

Drug analysis is an important part of analytical chemistry, which plays a significant role in drug quality control in clinical and pharmaceutical chemistry. Analysis of drug contents in various biological matrices is necessary in the cases of drug intoxication or suspicion of drug intoxication, drug addition and drug therapy or in anti-drug control [1]. It often happens that patients are treated simultaneously with several drugs representing different types [2]. The necessity of drugs monitoring in shortest time opens the opportunities of utilization of various analytical methods. Especially, the development of simple, sensitive and selective methods for simultaneous drug determination is of great interest and significance.

Paracetamol (N-acetyl-p-aminophenol, acetaminophen, PCM) is the most extensively used antipyretic and analgesic drug in the world [3], [4], [5]. It is an effective alternative for patients sensitive to aspirin and it is exploited to treat many difficulties such as headache, arthritis, colds, backache, toothaches and fevers. Because of the enormous interest of PCM for therapeutic purposes, its determination in biological samples and quality control in pharmaceuticals is very important [6]. Many analytical methodologies, such as titrimetric [7], [8], [9], spectrophotometric [10], [11], [12], [13], [14], [15], chemiluminescent [16], [17] and chromatographic [18], [19], [20], [21], [22], [23] methods have been employed for analyzing of PCM individually or simultaneously with other drugs. Generally, these methods are lengthy, overpriced, complicated, highly skilled and often too laborious, when the preconcentration step is included. Electrochemical methods have many inherent advantages such as simplicity, low cost and possibility to miniaturization that eliminate these limitations [2], [24]. These methods have also been developed for individual or simultaneous determination of PCM with other biologically active compounds [25], [26], [27], [28], [29], [30], [31]. In many cases it is safe to take PCM with other drugs simultaneously.

Penicillins belong to the most familiar group of antibiotics. They are present in drugs used for a number of infectious diseases [32], [33], [34]. Penicillin V (phenoxymethylpenicillin, PEN) comes under the group of small-spectrum β-lactam antibiotics. It kills a wide variety of bacteria that cause a wide variety of commonly occurring infections [35]. This drug may be used to treat infections of the lungs, mouth and throat, skin or soft tissue, or ears. Many analytical techniques for determination of various types of penicillins in body fluids and pharmaceuticals have been published. Generally, spectrophotometric [36], [37], [38], [39] methods and high-performance liquid chromatography (HPLC) with different modes of detection, such as ultraviolet detection [40], [41], [42] and mass spectrometry [43], [44], [45], [46], [47], belong to the most popular analytical methods for detection and quantification of penicillins. Despite significant importance in human life, on the basis of literature survey only few electrochemical studies dealing with penicillins are reported in comparison with other drugs. This is probably because oxidation of penicillins usually occurs as not clearly defined waves at a very high positive potential [48], [49], [50]. Streďanský et al. [51] published a concise report dealing with amperometric pH-sensing biosensors for urea, penicillin and oxalacetate. Some reports dealing with determination of penicillins are based on pulsed amperometric detection [52], [53], [54], flow injection analysis [55], [56], [57] and biosensors [58], [59], [60]. In daily life, the combined intake of PCM and PEN is used by patients in the treatment of some infections associated with fever.

Boron-doped diamond (BDD) is a modern electrode material that opens a novel branch of electrochemistry due to its excellent electrochemical features, such as low and stable background current over a wide potential range, corrosion and fouling resistance, high thermal conductivity, structural stability at extreme cathodic and anodic potentials, and high current densities [61], [62], [63], [64].

From our knowledge it is important to remark the fact that no official attempts for simultaneous determination of both drugs have been published yet to date in accessible literature. Owing to the significant effects and eventual abuse of studied drugs in human system, the square-wave voltammetry method able to quickly, sensitively and selectively determine PCM and PEN on bare BDD electrode was established. This simple and practical analytical approach is demonstrated on real samples of human urine.

Section snippets

Chemicals

PCM (CAS No. 103-90-2), PEN (87-08-1), glucose (50-48-7), urea (57-13-6), uric acid (69-93-2) and ascorbic acid (50-81-7) were obtained from Zentiva (Hlohovec, Slovak Republic) and used as received without any further purification. Various supporting electrolytes such as sulfuric acid, acetic acid, phosphate buffer, Britton–Robinson buffer and acetate buffer solutions were purchased from Lachema (Brno, Czech Republic). All reagents were of analytical grade. All aqueous solutions were made with

Electrochemical behavior of PCM and PEN on bare BDD electrode

It is well-known that simultaneous determination of electrochemically active compounds on bare electrodes is sometimes difficult due to overlapping of their voltammetric responses. First, CV measurements were performed for investigation of electrochemical behavior of PCM and PEN on bare BDD electrode. Fig. 1 illustrates CV voltammograms in the absence (curve a) and individually in the presence of 10 μM PCM (curve b) and 10 μM PEN (curve c) in acetate buffer solution (ABS) at pH 5.0. Concerning

Conclusions

The chemical modification can provide an advantage when selectivity is low on the bare electrode. However, the present paper has just demonstrated the successful application of bare BDD electrode as electrochemical sensor with no necessity of chemical modifications and electrochemical pretreatment for the simultaneous determination of PCM and PEN in human urine samples. Cyclic voltammetry and square-wave voltammetry were used for the characterization of electrochemical behavior, optimization of

Acknowledgements

This work was supported by the Grant Agency of the Slovak Republic (grant nos. 1/0182/11 and 1/0008/12) and Program for support young researchers (No. 6406).

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