Spectrophotometric determination of diclofenac in pharmaceutical preparations assisted by microwave oven

Abstract

In this work, an effective and low-cost method for the determination of sodium or potassium diclofenac is proposed in its pure form and in their pharmaceutical preparations. The method is based on the reaction between diclofenac and tetrachloro-p-benzoquinone (p-chloranil), in methanol medium. This reaction was accelerated by irradiating of reactional mixture with microwave energy (1100 W) during 27 seconds, producing a charge transfer complex with a maximum absorption at 535 nm. The optimal reaction conditions values such as reagent concentration, heating time and stability of the reaction product were determined. Beer's law is obeyed in a concentration range from of 1.25x10-4 to 2.00x10-3 mol l-1 with a correlation coefficient of 0.9993 and molar absorptivity of 0.49 x10³ l mol-1 cm-1. The limit of detection (LOD) was 1.35x10-5 mol l-1 and the limit of quantification (LOQ) was 4.49x10-5 mol l-1. In the presence of the common excipients, such as glucose, lactose, talc, starch, magnesium stearate, sodium sulphite, titanium dioxide, polyethyleneglycol, polyvinylpirrolidone, mannitol and benzilic alcohol no interferences were observed. The analytical results obtained by applying the proposed method compare very favorably with those given by the United States Pharmacopeia standard procedure. Recoveries of diclofenac from various pharmaceutical preparations were within 95.9% to 103.3%, with standard deviations ranging from 0.2% to 1.8%.

Evolution of microwave irradiation and its application in green chemistry and biosciences

“…The analytical data obtained by applying the proposed method was compared with those given by the United State Pharmacopeia (USP) standard procedure. Recoveries of diclofenac from various pharmaceutical preparations were within 95.9 to 103%, with standard deviations ranging from 0.2 to 1.8% [120,121].…”

Flow-Injection Spectrometric Determination of Sodium Diclofenac in Pharmaceutical Formulations

“…3 Thus sodium diclofenac importance for pharmaceutical industry and its widespread use, have been efforts to develop reliable methods for its determination. 4 Several batch methods are in literature to sodium diclofenac determination: potentiometric titration, 5 Ultra Violet (UV) spectrometry, 6,7 Liquid Chromatography (LC), 8 High Performance Liquid Chromatography (HPLC), 9,10 Digital Image-Based Flame Emission Spectrometry (DIB-FES), 11 Flame Atomic Absorption Spectrometry (FAAS), 3 Capillary Electrophoresis (CE), 12,13 Liquid Chromatography Atmospheric-Pressure Chemical Ionization Mass Spectrometry (LC-APCI-MS), 14 Differential Scanning Calorimetry (DSC), 15 Nuclear Magnetic Resonance (NMR), 16 Fluorescence, 17 Near Infrared (NIR) spectrometry 18 and voltammetry. 19,20 The majority of previously mentioned methods are expensive with high maintenance cost making them less attractive to routine analysis.…”

“…Regarding simplicity, cost of instrumentation and maintenance, Visible (VIS) Spectrometry arises as an interesting and accessible alternative for routine analysis in industry and teaching due to its reasonable sensitivity, 4 selectivity and specificity. Same as other techniques, several visible spectrometric batch methods for sodium diclofenac determination have been reported.…”

“…Same as other techniques, several visible spectrometric batch methods for sodium diclofenac determination have been reported. 4,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] However, several of these methods consist on elaborated procedures with manipulation steps.…”