Iodine as an oxidimetric reagent for the determination of thiosemicarbazide and its derivatives

A sensitive, accurate and reproducible method for the determination of 10–1000 µg of thiosemicarbazide (TSC), 1-acetylthiosemicarbazide (1-ATSC), 1-phenylthiosemicarbazide (1-PTSC) and 4-phenylthiosemicarbazide (4-PTSC), involving an amplification reaction, is described. The method is based on the oxidation of the thiosemicarbazide compounds, in a hydrogen carbonate medium, with a chloroform solution of iodine, removal of the excess, oxidation with bromine of the iodide formed and titrimetric determination of the liberated iodate after six-fold amplification. The oxidation reactions involve a ten-electron change per molecule of TSC, 1-PTSC or 4-PTSC and an eight-electron change per molecule of 1-ATSC.