抄録
A method for the rapid determination of micro amounts of thiourea in ammonium thiocyanate has been investigated by means of the short-circuit amperometric argentometric titration. A rotating (1200 rpm) platinum wire electrode and a mercury-mercury(II) iodide electrode (-0.23 V vs. SCE) were used.
By this technique 5 × 10-5 F thiourea in the presence of an 800-fold amount of thiocyanate could be titrated directly with the relative error of +0.1% and the coefficient of variation (c. v.) of 0.3% at 5060°C in a solution containing 0.5 F ammonia, 0.025 F ammonium carbonate and 0.02% gelatin.By applying the standard addition method 2.5 × 10-6 F thiourea in the presence of a 12000-fold amount of ammonium thiocyanate could be determined with the relative error of +2.7% and c. v. of 3.5%. This method was applied to the analysis of thiourea in some commercial ammonium thiocyanate(industrial and reagent grade).
