Determination of sulphacetamide, sulphadimidine or sulphathiourea in the presence of their degradation products using first derivative spectrophotometry.

A method is presented for the determination of sulphacetamide sodium, sulphadimidine and sulphathiourea in the presence of their acid-induced degradation products using first derivative spectrophotometry. By measuring the absolute value of the first derivative curves at the zero contribution of the corresponding degradation products, the concentration of the intact drug can be calculated directly without interference of the degradation product. The validity of the method was confirmed using synthetic mixtures of the intact drugs with their degradation products.

Application of orthogonal functions to the determination of prednisolone and hydrocortisone in some pharmaceutical preparations.

Glenn's method of orthogonal functions has been successfully applied to the direct spectrophotometric determination of the title compounds in presence of phenylephrine and/or neomycin sulphate without preliminary separation. The proposed methods when applied to the analysis of market preparations are in good agreement with those of the triphenyltetrazolium colour reaction recommended as the official method.