FIELD: analysis of natural waters and sewage contaminated with high-toxic chemical substances, such as dimethylhydrazine and product of its oxidation - nitrosodimethylamine. SUBSTANCE: aqueous solution of nitrosodimethylamine is mixed with zinc in presence of sodium hydroxide in the course of 1.0-3.0 min with proportion of water to sodium hydroxide and zinc equal to 1: (0.013-0.047): (0.005-0.15) correspondingly. Reaction solution after separation of zinc is injected with hydroxylamine with mass proportion of solution; hydroxylamine 1.0-0.02 and sodium hydroxide with mass proportion of water to total content of sodium hydroxide equal to 1:(0.23-0.33) followed by blow-away of formed asymmetric dimethylhydrazine into mixture of paranitrobenzaldehyde, ethyleneglycol and acetic acid and its subsequent colorimetering. EFFECT: enhanced authenticity. 2 tbl
