Spectrophotometric Determination of Five Commercial Drugs in Pure Form and Pharmaceutical Formulations by Ion-Pair Complexation with Alizarin Red S

[摘要] Simple, accurate, selective and rapid spectrophotometric methods have been developed for the determination of itopride, midodrine, diclofenac, mesalamine and sumatriptan in their pure as well as in pharmaceutical dosage forms. The method was based on ion-pair complex formation between the drugs and anionic dye, alizarin red S in an acidic medium (pH 2.0-4.0). The complexes formed were quantitatively extracted into chloroform and measured at 284, 287, 279, 285 and 280 nm wavelength for itopride, midodrine, diclofenac, mesalamine and sumatriptan respectively. Beer’s law was obeyed in the concentration range of 3.5-35 µg mL-1 for itopride and diclofenac, 2.5-180 µg mL-1 for midodrine, 3.0-80 µg mL-1 for mesalamine and 4.0-200 µg mL-1 for sumatriptan. The stoichiometry of the complexes formed between the drugs and the dye was 1:1 as determined by Job’s method of continuous variation. The association constant (KIP) of the ion-pair complexes formed was evaluated using Benesi-Hildebrand equation. Limit of detection, limit of quantification and Sandell’s sensitivity of the methods were also estimated. The proposed methods were successfully employed for the determination of these drugs in their pharmaceutical dosage form

[学科分类] 分析化学

[关键词] Drugs;Alizarin Red S;Ion-pair complex;Spectrophotometry