Abstract

Three different methods of sulfide analysis were subjected to statistical comparisons. These methods were: (1) titration with potassium ferricyanide using as indicator the ferrous complex of dimethylglyoxime; (2) concentration measurement of sulfide from the potential of a sulfide ion electrode; (3) titration with silver nitrate with the sulfide ion electrode as an indicator. Firstly, two characteristics of the methods, namely the precision and accuracy, were studied using tests of significance. Secondly, sources of disturbance of the ferricyanide method were studied using the analysis of variance. The first of these methods was found to be the most precise. The direct potentiometric method is, according to the results, the most imprecise. As far as the accuracy is concerned, the titration with silver nitrate is probably the only quite accurate method in the statistical sense. The results obtained in the analysis of variance show that sulphite cannot be considered as an interfering ion in the titration with potassium ferricyanide.