Stability-indicating assay for oxyphenbutazone. Part I. Thin-layer chromatographic determination of oxyphenbutazone and its degradation products

Abstract

A high-performance thin-layer chromatographic procedure for the separation and determination of oxyphenbutazone and its six main potential degradation products in situ is reported. The method avoids degradation of oxyphenbutazone in situ by chelating iron in the silica plate and allows the simultaneous assay of oxyphenbutazone and its decomposition products using a chromatographic spectrophotometer. The method has been validated as a stability-indicating assay of oxyphenbutazone in tablets and capsules. It allows the determination of 0.5% of decomposition products (with respect to oxyphenbutazone). In the formulations analysed, only trace amounts of two oxidation products were found.