Simultaneous spectrophotometric determination of hydrazine and phenylhydrazine based on their condensation reactions with different aromatic aldehydes in micellar media using H-point standard addition method

H-point standard addition method (HPSAM) was applied to the simultaneous determination of hydrazine and phenylhydrazine. The method is based on the hydrazone formation reactions of hydrazine and phenylhydrazine in the presence of micellar sodium dodecyl sulfate (SDS). Mixed reagents of p-(dimethylamino)benzaldehyde (DAB) and p-nitrobenzaldehyde (NB) was used as selective chromogenic reagents for hydrazine and phenylhydrazine. Hydrazine and phenylhydrazine can be determined simultaneously in the range 0.020–0.50 and 0.20–10.0 μg ml−1, respectively. The results allowed that simultaneous determination could be performed with the ratio 1:500 to 1:10 hydrazine–phenylhydrazine. Under working conditions, the proposed method was successfully applied to the simultaneous determination of hydrazine and phenylhydrazine in several synthetic mixtures and plasma and water samples.