Indirect determination of thiocyanate with ammonium sulfate and ethanol byextraction-flotation of copper

A new method for the indirect determination of thiocyanate with ammonium su lfate and ethanol by extraction-flotation of copper in the presence of asco rbic acid is described. A small amount of Cu(ii) is reduced to Cu(i) by asc orbic acid, then Cu(i) is precipitated with SCN-. In the course of phase se paration of ethanol from water, the precipitated CuSCN stays in the interfa ce of ethanol and water. A good linear relationship is observed between the flotation yield of Cu(ii) and the amount of SCN-. Using 1.0 ml of 1 x 10(- 3) M ascorbic acid solution, 50 mu g of Cu(ii), 3.5 g of (NH4)(2)SO4 and 3. 0 ml of ethanol with a total volume of 10 ml, the concentration of thiocyan ate could then be determined by determining the flotation yield of Cu(ii). The detection limit for thiocyanate is 5 x 10(-5) M. Every parameter was op timized and the reaction mechanism was studied. The method is simple and ra pid and it was successfully applied to the determination of thiocyanate in urine and saliva of smokers and non-smokers and in venous blood of patients infused with sodium nitroprusside.