Analysis of steroids. Part XXII. A specific method for the determination of 21-halo corticosteroid derivatives and related compounds

Abstract

A specific spectrophotometric method has been developed for the determination of 21-halo corticosteroid derivatives and the sulphonic acid esters of 21-hydroxy corticosteroids. The method is based on the conversion of these compounds into 21-quaternary pyridinium salts and measurement of the latter spectrophotometrically in alkaline media as the yellow “quaternary pyridinium enolates”.

The absorption maxima of different corticosteroid derivatives are between 413 and 417 nm, while the molar extinction coefficients range between 20 240 and 21 900. The coefficient of variation has been found to be 0·7 per cent.

The method permits the determination of the above compounds present as contaminants in corticosteroids at the level of 0·1 per cent. The application of the method to non-steroidal α-haloketones is also given.