Express standardization of sulfide solutions using voltammetric titration on two points

A new method called voltammetric titration on two points for express (<= 5 min) standardization of unstable sulfide solutions has been developed. The method can be used as an alternative to the classical K-3[Fe(CN)(6)] titration. The same redox reaction underlies the new method: 2[Fe(CN)(6)](3-) + S2- -> /2[Fe(CN)(6)](4-) + S-0. The analytical signal, current of ferricyanide reduction, is used for immediate calculation of the sulfide concentration. Two analytical signals of electrochemically active K-3[Fe(CN)(6)] before (I-0) and after (I-1) its quantitative interaction with the analyzable sample is enough to get an accurate concentration. The method accuracy has been confirmed by comparison of experimental (Delta(exp)) and calculated (Delta(calc)) data, and with recovery study.