Abstract

New methods have been developed for determining and/or speciating several important inorganic sulphur species, including: thiosulphate, sulphate, sulphite, sulphide and polysulphide in kraft pulping liquors and effluents by capillary zone electrophoresis. In addition, several other key anions, including: hydroxide, carbonate, oxalate, formate and chloride can be quantified in the same process liquors. Two approaches were developed for determining the anions. In one method, anions were baseline resolved and quantified using sodium chromate, tetradecyltrimethylammonium hydroxide-based electrolytes with indirect UV-detection. In the second scheme, polysulphide was speciated, and sulphur species such as sulphide, thiosulphate and sulphite, as well as hydroxide were separated and determined using a sodium sulphate, tetradecyltrimethylammonium hydroxide-based electrolyte with direct UV-detection. A third approach, involving the use a 2- (N-Cyclohexylamino) ethanesulfonic acid, hexamethonium hydroxide electrolyte with conductivity detection was also briefly examined and found to be unsuitable for the analysis of sulphide-bearing samples.