Electrochemical Determination of Meloxicam in Pharmaceutical Preparation and Biological Fluids Using Oxidized Glassy Carbon Electrodes

Abstract

Meloxicam (MLC), 4-hydroxy-2-methyl-N-(5-methyl-2-thiazolyl)-2H-1,2-benzo thiazine-3-carboxamide-1,1-dioxide, is a highly potent non-steroidal anti-inflammatory drug (NSAID) of the enolic acid class of oxicam derivatives. 1,2) This drug is indicated for the treatment of rheumatoid arthritis, osteoarthritis, and other joint diseases.2) Due to the vital importance of MLC determination in pharmaceutical preparations and in biological fluids, many analytical techniques have been reported in literature. MLC has been determined in pharmaceutical preparations using spectroscopic, [3][4][5][6][7] HPLC [8][9][10][11][12][13] and electrochemical [14][15][16][17][18] methods. Studies of the therapeutic and toxic effects of drugs require a sensitive method for determination of them at a trace level. All reported spectroscopic methods suffer from low sensitivity. On the other hand, high performance liquid chromatographic methods, while having the advantage of requiring minimal sample preparation, are relatively slow and expensive, require filtration, degassing and expensive grades of reagents, eluents and equipment. In addition, the most of the reported electrochemical methods are based on the reduction of MLC on dropping or hanging mercury electrodes. Radi et al. have developed an electrochemical oxidation method for determination of MLC in tablet dosage form using a carbon paste electrode.16) According to this report, MLC is irreversibly oxidized from amide and enol functions over pH range 2-11.5 in buffer media. Adsorptive stripping voltammetry has been demonstrated as a sensitive analytical method for a wide range of pharmaceutical compounds adsorbing on the electrode surface.19) As a result, a wide variety of substances possessing surface-active properties are easily measurable at very low concentration levels.20) The adsorptive properties of a glassy carbon electrode can be changed with the electrochemical pretreatment procedure. Electrode surface modifications and pretreatments have been widely used to improve the electrochemical responses of biological compounds and to construct electrochemical detectors for liquid chromatography involving the detection of analytes that oxidize only at extreme positive potentials. [21][22][23] The behavior of carbon electrodes at high positive potentials has received considerable interest owing to a desire to improve both the activity and reproducibility of carbon electrodes. The objective of the present work was to develop an adsorptive stripping voltammetric procedure for the determination of MLC, with higher sensitivity than the reported ones. It has been found that MLC could be adsorbed on an electrochemically pretreated glassy carbon electrode (EPGCE). Using this phenomenon and by accumulating this compound at the electrode surface prior to a differential pulse voltammetry and linear sweep voltammetry measurements, a higher sensitivity has been readily achieved. This work deals with the application of the proposed voltammetric methods to assay MLC in biological samples and pharm...

XPS analysis of glassy carbon electrodes chemically modified with 8‐hydroxyquinoline‐5‐sulphonic acid

“…Broad peaks such as those present in the voltammetric profile relevant to GC/ox electrodes (dotted line in Fig. ) were already reported in previous investigations relevant to electrochemically activated GC electrodes, and attributed to redox reactions of oxygen surface sites resulting from the applied electrochemical treatments . The same broad peaks are still present, even if more intense, in the voltammogram recorded at GC/HQSA electrodes which, in addition, are characterized by two additional peak couples, a/a′ and, respectively, b/b′ attributed to HQSA redox intermediates .…”

“…This because of the adsorption capabilities made possible through electrostatic attraction and/or ion exchange between the negatively charged sulfonic acid functionality of HQSA and the positively charged groups of the analytes. It is well known, from investigations performed in different support electrolytes, that cycling GC electrodes in wide potential ranges such as the one used in our work (Refs. and the Experimental section), can also induce complex redox reactions on the GC electrode surface itself, even in the absence of HQSA.…”

“… and the Experimental section), can also induce complex redox reactions on the GC electrode surface itself, even in the absence of HQSA. These reactions produce electrochemically active surface functional groups such as quinones, quinone‐like, phenolic and/or alcoholic groups …”

Electrochemical Determination of Acetaminophen at the Surface of a Glassy Carbon Electrode Modified With Multi-Walled Carbon Nanotube

“…Electrode surface modification and pretreatments have been widely used to improve the electrochemical responses of biological compounds 23 . For example, CNT-modified GCEs provide a stable and sensitive electrochemical response for phenols 24 , NADH 25 , estrogenic phenolic compounds 26,27 , dopamine 28 , uric acid 28 and tetracycline 29 .…”

Ultra Sensitive Liquid Chromatographic Method for the Simultaneous Determination of Carbamazepine with Nsaids in API, Pharmaceutical Formulation and Human Serum by Programming the Detector: Application to In Vitro Drug Interaction

“…Variety of techniques have been reported in literature for the determination of MEL including spectrophotometric and fluorimetric methods [9], flow-injection technique [10], electrochemical determination [11], HPLC-UV [12,13], LC-MS [14,15]. The methods have also been reported for the quantitation of IBU in commercial formulation and body fluids such as capillary isotachophoresis [16], spectrofluorometric determination [17], LC [18,19], spectrophotometric assay [20].…”