FIELD: environmental monitoring. SUBSTANCE: substance subjected to analysis is treated with 0.5-1.5% hydroxylamine hydrochloride aqueous solution at sodium (potassium) hydroxide/ water weight ratio 1:(3-4.6), after which mixture is boiled in inert gas or air flow and vapor is then condensed by passing it through 0.45-0.62% solution of p-nitrobenzaldehyde mixed with acetic acid and ethylene glycol at volume ratio 1:(4-5). EFFECT: considerably reduced analysis time, improved its accuracy, and eliminated deficiency of starting reagent. 2 tbl
