SELECTIVE ASSAY PROCEDURE FOR CHLORPROPAMIDE IN PRESENCE OF ITS DECOMPOSITION PRODUCTS

A colorimetric method for the quantitative determination of chlorpropamide in the presence of its decomposition products is described. The procedure is based on the interaction of n‐propylamine (liberated in situ from chlorpropamide) and ninhydrin to form a blue color which is measured spectrophotometrically at 584 mμ. No color is produced by p‐chlorobenzenesulfonamide or di‐n‐propylurea, two possible decomposition products of chlor‐propamide, n‐Propylamine, which may be present in decomposed samples, is removed by aqueous acid extraction prior to color development thus making the analytical procedure specific for unchanged chlorpropamide. The merits of the colorimetric procedure over conventional ultraviolet‐spectrophotometric procedures are shown by analysis of chlorpropamide tablets which had been subjected to excess heat and moisture. A thin‐layer chromatographic procedure for the separation and detection of chlorpropamide and its possible decomposition products is described. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company