Plastic membrane electrode for selective determination of diclofenac (voltaren) in pharmaceutical preparations

Abstract

A novel plastic membrane ion-selective electrode for determining the diclofenac anion is described. The sensing membrane of the electrode consists of diclofenac-nickel(rr) bathophenanthroline as an ion-exchanger site in a poly(viny1 chloride) matrix plasticized with o-nitrophenyl phenyl ether. In borate buffer solutions of pH 8-12, the electrode exhibits a fast, stable and linear response for 1 X 10-t5 X 10-5 mol dm-3 diclofenac with an anionic slope of 55.1 k 0.2 mV decade-' at 25 OC. Potentiometric selectivity measurements revealed negligible interferences from 14 different anions including aromatic and aliphatic carboxylic acid salts. The electrode displays useful analytical characteristics for the direct determination of diclofenac in various pharmaceutical preparations. Results with an average recovery of 98 +, 0.6% of the nominal value were obtained.

Iron(II)-phthalocyanine as a novel recognition sensor for selective potentiometric determination of diclofenac and warfarin drugs

“…Potentiometric sensors for determining both drugs are very limited and those published are based on the use of ferroin-drug associate complexes [36][37][38]. Selectivity of sensors based on ion-association complexes is low and suffer from interferences by many common ions.…”

Potentiometric behaviour of ion selective electrodes based on iron porphyrins: The influence of porphyrin substituents on the response properties and analytical determination of diclofenac in pharmaceutical formulations

“…From all those techniques, potentiometric methods, resorting to ion selective electrodes (ISEs) are considered an advantageous analytical tool, especially for the analysis of complex matrices such as pharmaceutical preparations [35], mainly considering its selectivity, price and analytical range. Some potentiometric studies have already been performed using diclofenac selective electrodes based on bathofenantroline [28] and cyclodextrin [30], and some other trials were carried out in non-aqueous media by indirect titration of the mentioned anti-inflammatory agent [29]. However, as far as we know, no diclofenac selective electrode, based on metalloporphyrins, is referred to in literature.…”

“…As a result, this non-steroidal drug presents anti-inflammatory, analgesic and antipyretic properties [13] being often used as an adjuvant on the treatment of chronic diseases like arthritis and glaucoma. Regarding its therapeutic relevance different methodologies have been proposed for the determination of sodium diclofenac in pharmaceutical formulations, namely spectrophotometry [14][15][16][17][18][19][20][21][22][23], fluorimetry [24][25][26][27], potentiometry [28][29][30], chromatography [31][32][33], and nuclear magnetic resonance spectroscopy [34]. From all those techniques, potentiometric methods, resorting to ion selective electrodes (ISEs) are considered an advantageous analytical tool, especially for the analysis of complex matrices such as pharmaceutical preparations [35], mainly considering its selectivity, price and analytical range.…”

Voltammetric response of diclofenac-molecularly imprinted film modified carbon electrodes

“…Although analysis with chemical sensors is nowadays a major research area [12], only potentiometric [13,14] and flow-through spectrophotometric [15] sensors have been developed for diclofenac determination. In order to obtain highly selective sensors two main challenges should be achieved i.e.…”