FIELD: analytical methods. SUBSTANCE: electrochemical method of determining nitrite ion in solution using ion-selective electrodes is based on oxidizing iodide ion to elementary iodine with nitrite ion followed by gas extraction and absorption of iodine. According to invention, 25 to 2500-fold excess of iodide ion with respect to nitrite ion is applied and gas extraction is performed in inert gas (nitrogen or argon) flow. Resulting elementary iodine is absorbed by sodium sulfite. Quantity of absorbed iodine is measured by means of iodide-selective electrode. To avoid deteriorating effect of sulfite ion on membrane of iodide- selective electrode, absorption solution, after extraction of iodine, is mixed, in 1:1 proportion, with perborate buffer solution containing in 1 l: 62 g of boric acid, 120 ml of 10% sodium hydroxide, and 170 ml of 30% hydrogen peroxide. EFFECT: increased sensitivity and selectivity of analysis. 3 cl, 1 dwg, 5 tbl
