Bengi Uslu

Analysis of Pharmaceuticals and Biological Fluids Using Modern Electroanalytical Techniques

A review of the principles and application of modern electroanalytical techniques, namely, cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, differential pulse polarography, square wave voltammetry, square wave polarography, stripping voltammetric, and stripping polarographic techniques, is presented. The use and advantages of these techniques at different electrodes are discussed. The analytical applications of these techniques to pharmaceutical compounds in dosage forms and biological media are also discussed. Various selected studies on these subjects since 1995 are reviewed.

Electroanalytical Application of Carbon Based Electrodes to the Pharmaceuticals

Abstract Carbon and its derivatives, as the high performance material, occupy a special place in electrochemistry due to its ‐in many ways‐ extreme properties. Recent trends and advances in the electrochemistry of carbon‐based electrodes are reviewed. The varieties of carbon‐based electrodes, their basic physicochemical properties and some characteristics are surveyed. Special attention is paid to the possibilities of carbon‐based electrodes in electroanalytical investigation in pharmaceutical dosage forms and biological samples using modern electrochemical techniques. This review includes a summary of the rules that must be considered for drug analysis from its dosage forms and biological samples using carbon‐based electrodes. The present review is the first comprehensive report on the heterogeneous and homogeneous carbon electrodes, and an addition to many excellent reviews on carbon electrodes in the literature. This review summarizes some of the recent developments and applications of carbon‐based electrodes for drug compounds in their dosage forms and in biological samples in the period from 1996 till 2006. Also some further selected designs (screen‐printed; carbon nanotubes, etc.) and applications have been discussed.

Solid Electrodes in Electroanalytical Chemistry: Present Applications and Prospects for High Throughput Screening of Drug Compounds

This review summarizes recent progress in the development and application of solid electrodes to the screening of pharmaceutical dosage forms and biological fluids. Recent trends and advances in the electroanalytical chemistry of solid electrodes, microelectrodes and electrochemical sensors are reviewed. The varieties of solid electrodes and their basic physico-chemical properties and some specific characteristics including some supramolecular phenomena at their surface are surveyed. This review also includes some selected designs and their applications. Despite many reviews about individual solid electrodes in the literature, this review offers the first comprehensive report on all forms of solid electrodes. Special attention is paid to the possibilities of solid electrodes in high throughput electroanalytical investigation of drug dosage forms and biological samples using modern electroanalytical techniques. Various selected studies on these subjects since 1996 are reviewed in this paper.

Electroanalytical Methods for the Determination of Pharmaceuticals: A Review of Recent Trends and Developments

Electroanalysis is a powerful analytical technique that is increasing in utility in the pharmaceutical industry. It is used as an alternative or complementary technique to spectrophotometric and separation techniques due to its high sensitivity, speed of analysis, reduction in solvent and sample consumption, and low operating cost compared to other analytical methods. A review of the principles and application of modern electroanalytical techniques, namely, cyclic, linear sweep, differential pulse, square wave and stripping voltammetric techniques, is presented. This review gives recent pharmaceutical analysis applications used for each mode of electroanalytical chemistry. The review will also describe recent developments for enhancing concentration limits of detection, electrode types, and so forth. Selected studies on these subjects are given as examples.

Electroanalytical characteristics of antipsychotic drug ziprasidone and its determination in pharmaceuticals and serum samples on solid electrodes.

Ziprasidone is a psychotropic agent used for the treatment of schizophrenia. Its oxidation was investigated electrochemically at boron-doped diamond and glassy carbon electrodes using cyclic, differential pulse, and square wave voltammetry. The dependence of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were examined. The process was diffusion and adsorption controlled for boron-doped diamond and glassy carbon electrodes, respectively. The possible mechanism of oxidation was discussed with some model compounds that have indole and piperazine oxidations. A linear response was obtained between 8 x 10(-7) and 8 x 10(-5) M for the first peak in acetate buffer (pH 5.5) and between 2 x 10(-6) and 2 x 10(-4) M for the second peak in 0.1 M H(2)SO(4) with boron-doped diamond electrode for differential pulse and square wave voltammetric techniques. The reproducibility and accuracy of the proposed methods were found between 0.31 and 1.20, 99.27 and 100.22, respectively. The recovery studies were also achieved to check selectivity and accuracy of the methods. The proposed methods were applied for the determination of ziprasidone from pharmaceutical dosage forms and human serum samples without any time-consuming extraction, separation, evaporation or adsorption steps prior to drug assay except precipitation of the proteins using acetonitrile. The results were statistically compared with those obtained through an established LC-UV technique, no significant differences were been found between the voltammetric and LC methods.

Voltammetric studies on the HIV-1 inhibitory drug Efavirenz: The interaction between dsDNA and drug using electrochemical DNA biosensor and adsorptive stripping voltammetric determination on disposable pencil graphite electrode

The interaction of Efavirenz (EFV) with fish sperm dsDNA immobilized onto pencil graphite electrode (PGE) has been studied by using differential pulse voltammetric technique using an electrochemical DNA biosensor. The guanine signal was lower with (double stranded-DNA) dsDNA-treated PGE than the untreated electrode after the interaction with EFV occurred. The changes in the experimental parameters such as the accumulation time and the concentration of EFV were also studied. All necessary parameters such as sensitivity, selectivity, accuracy and precision were calculated. In addition, the detection and determination limits, reproducibility and applicability of the analysis to pharmaceutical dosage forms were also investigated. These results showed that this DNA biosensor could be used for the sensitive, rapid simple and cost effective detection and determination of EFV-dsDNA interaction. The linearity was between 2 and 24 ppm of EFV concentration on guanine signal decreasing curve. EFV showed an irreversible oxidation behavior at all investigated pH values. This oxidation step was adsorption controlled on PGE. Hence, differential pulse adsorptive stripping (AdsDPV) voltammetric method was developed for the determination of EFV. Accumulation time and potential were optimized. Under these conditions, the current showed a linear dependence with concentration in the range between 0.018 and 2.56 ppm. Both determination methods were fully validated and applied for the analysis of EFV pharmaceutical dosage form.

Voltammetric investigation of Tamsulosin.

The electrooxidative behavior and determination of Tamsulosin HCl (TAM), one of the alpha(1)-adrenoceptor antagonist, on a glassy carbon disc electrode were investigated for the first time by using cyclic, linear sweep, differential pulse (DPV) and square wave voltammetry (SWV). TAM showed an irreversible oxidation behavior at all pH values and buffers studied. From the electrochemical response, the main oxidation step was found to be related to the methoxy group on the phenyl ring. DPV and SWV were used to generate peak current versus concentration curves for TAM. A linear response was obtained in the range comprised between 2x10(-6) and 4x10(-4) M for both techniques with detection limit of 3.34x10(-7) M for DPV and 2.45x10(-7) M for SWV. The methods were proposed for the determination of TAM in dosage forms adopting both DPV and SWV modes. The methods were extended to the in vitro determination of TAM in spiked serum samples.

Electroanalytical investigation and determination of pefloxacin in pharmaceuticals and serum at boron-doped diamond and glassy carbon electrodes

The anodic behavior and determination of pefloxacin on boron-doped diamond and glassy carbon electrodes were investigated using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. In cyclic voltammetry, pefloxacin shows one main irreversible oxidation peak and additional one irreversible ill-defined wave depending on pH values for both electrodes. The results indicate that the process of pefloxacin is irreversible and diffusion controlled on boron-doped diamond electrode and irreversible but adsorption controlled on glassy carbon electrode. The peak current is found to be linear over the range of concentration 2x10(-6) to 2x10(-4)M in 0.5M H(2)SO(4) at about +1.20V (versus Ag/AgCl) for differential pulse and square wave voltammetric technique using boron-doped diamond electrode. The repeatability, reproducibility, precision and accuracy of the methods in all media were investigated. Selectivity, precision and accuracy of the developed methods were also checked by recovery studies. The procedures were successfully applied to the determination of the drug in pharmaceutical dosage forms and humans serum samples with good recovery results. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage forms and biological samples, respectively.

Electrochemical reduction and oxidation of the antibiotic cefepime at a carbon electrode

The O-methyl oxime grouping in the antibiotic cefepime is reduced in aqueous buffer solution at pH < 8 at a carbon electrode. The reduction of the protonated form of the oxime occurs in a single two-electron step. By comparison with anodic wave of 2-aminothiazole it was furthermore shown that the oxidation of cefepime involves the 2-amino group located on the thiazole ring in the side chain on C-7. Both reduction and oxidation peaks can be used for analytical purposes.

Anodic oxidation of etodolac and its square wave and differential pulse voltammetric determination in pharmaceuticals and human serum

A voltammetric study of the oxidation of etodolac has been carried out at the glassy carbon electrode. The electrochemical oxidation of etodolac was investigated by cyclic, linear sweep, differential pulse and square wave voltammetry using glassy carbon electrode. Different parameters were tested to optimize the conditions for the determination of etodolac. The dependence of intensities of currents and potentials on pH, concentration, scan rate, nature of the buffer was investigated. For analytical purposes, a very well resolved diffusion controlled voltammetric peak was obtained in Britton-Robinson buffer at pH 2.15 for differential pulse and square wave voltammetric techniques. The linear response was obtained in the ranges of 2.10(-6)-8.10(-5) M with a detection limit of 6.8x10(-7) and 6x10(-6)-8x10(-5) M with a detection limit of 1.1x10(-6) M for differential pulse and square wave voltammetric techniques, respectively. Based on this study, simple, rapid, selective and sensitive two voltammetric methods were developed for the determination of the etodolac in tablet dosage form and human serum.