Diclofenac Sodium Determination in Pharmaceutical Preparations After Complexation With Calcium and Magnesium and Molecular Modelling Study.
Abstract The study was carried out for indirect determination of diclofenac sodium in preparations after complexation with Ca or Mg. The diclofenac was treated with the metals individually and the metal complexes formed as precipitates were extracted in chloroform or separated by centrifugation. A decrease in concentration of metal ions was observed in aqueous phase which was correlated with concentration of diclofenac sodium. The complexation reactions were optimized in terms of pH, nature of metal ion, extraction in chloroform or separation by centrifugation. The decrease in concentration of metal ions in aqueous phase was monitored using flame Atomic Absorption Spectrophotometry (AAS) or by complexometric titration with EDTA. The linear calibration range observed were from 40-200 µg /mland 40-200 ug/mL diclofenac sodium respectively by using both Ca and Mg. The limit of detection was 15 µg /mL diclofenac using Ca or Mg ions using both solvent extraction and precipitation methods with AAS. The method was repeatable with interday and intraday reproducibility with relative standard deviation within 5%. The method was applied for the determination of diclofenac from pharmaceutical preparations, Voltral, Voren, Qufen, Dicloplus, Dicloran with RSD% 1.3%-8.2%.