Assay of hydrazine in isoniazid and its formulations by difference spectrophotometry

Abstract

A rapid procedure is described for the determination of hydrazine at the very low levels that may occur as a result of hydrolysis in certain isoniazid formulations. The method is based upon the measurement of the absorbance difference between a solution of the 4-dimethylaminobenzalazine derivative of hydrazine and a similarly prepared solution containing 3%V/V acetone. The absorbance difference, which is proportional to the concentration of hydrazine, is unaffected by the presence of a large excess of isoniazid. The choice of experimental conditions which provide the maximum accuracy, sensitivity and specificity is discussed.