FIELD: analytical chemistry. SUBSTANCE: method involves addition of sulfamic acid, sodium hydrogen phosphate, starch and potassium iodide to an examined sample at their mass ratio = 1:(0.8 x 10-2 - 1.2 x 10-2):(0.8 x 10-2 - 1.2 x 10-2):(0.4 x 10-3 - 0.6 x 10-3):(0.5 x 10-2 - 0.7 x 10-2), respectively. The obtained solution is subjected for photometry at wavelength 590 nm. Method can be used for control over environment pollutions. EFFECT: high selectivity of method, express-analysis. 2 tbl
