Spectrophotometric determination of hydrazine and 1,1-dimethylhydrazine,separately or in admixture

A rapid, sensitive spectrophotometric method for the determination of hydrazine and 1,1-dimethylhydrazine, separately or in mixtures of varying proportions, is described. The analysis is based on the well-known reaction of these compounds with salicylaldehyde to form, in the case of hydrazine, a symmetrical azine, or with 1,l-dimethylhydrazine, a hydrazone. Absorbance measurements were made in the ultraviolet at wavelengths characteristic of the derivatives and of salicylaldehyde; the results were calculated by means of simultaneous equations. The procedure is sensitive to concentrations of hydrazine as low as 0.3 μg/ml and of 1,1-dimethylhydrazine as low as 0.25 μg/ml. This corresponds to initial sample solutions having a concentration of 3.0 mg of hydrazine and 1.25 mg of 1,1-dimethyl hydrazine per ml.