INDIRECT DETERMINATION OF TRACES OF THIOCYANATE BY IODOMETRY AND DIFFERENTIAL-PULSE POLAROGRAPHIC METHOD

Two methods are described for the indirect determination of thiocyanat e in aqueous media down to ca. 0.01 mu g/ml. Both methods involve oxid ation of thiocyanate by iodine under specified conditions, to yield io dide. In the first method, the iodide ions are quantitatively oxidised to iodate which is allowed to undergo the Leipert reaction and the li berated 18 I-2 molecules are titrated as usual with thiosulphate. In t he second method, the iodate-containing solution is adjusted at pH 1.4 and measured by differential-pulse polarography under optimum conditi ons. The two methods enable the accurate determination of quantities a s low as 0.02- 1.0 mu g/ml SCN- with average recoveries of 100.0 and 1 00.1% and relative standard deviations of 1.7 and 1.0, respectively.