Micellar Electrokinetic Chromatography as a Valuable Technique for the Quality Control of Drugs Based on the Combination of Sulfamethoxazole with Trimethoprim

摘要

A micellar electrokinetic chromatographic method is presented for the determination of sulfanilic acid and sulphanilamide as degradation products of sulfamethoxazole and of 3,4,5-trimethoxybenzoic acid as degradation product of trimetoprim, by using 15 mM phosphate buffer (pH 12.6), 20 mM sodium dodecylsulfate and 5% (v/v) acetonitrile as electrolyte. The separation was carried out at 25 kV and 25 °C in a fused silica capillary (60.2 cm × 75 μm i.d.). Under these conditions, the run time was less than 10 min and the limits of quantification were 2.0–4.2 mg L−1. The reproducibility in-a-day of the assay was excellent because the relative standard deviations of the peak areas were always under 3%. The method was applied to spiked samples of a pharmaceutical commercial preparation containing the sulfamethoxazole-trimethoprim combination, and the recoveries obtained were close to 100% for both sulfanilic acid and sulfanilamide.