Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9748473 | Journal of Chromatography A | 2005 | 6 Pages |
Abstract
In this paper, a capillary zone electrophoretic (CZE) method was developed for the separation of the sulfur species dithionite (S2O42â), sulfite (SO32â), sulfate (SO42â) and thiosulfate (S2O32â). A carrier electrolyte (pH 7.0) containing 1.5 mmol Lâ1 pyromellitic (PM) acid, 10 mmol Lâ1 Tris(hydroxymethyl)-aminomethane (Tris), 0.5 mmol Lâ1 diethylenetriamine (DETA) and 0.1% (v/v) formaldehyde (as stabilizer for S2O42â and SO32â) allowed the determination of the sulfur anions after 9 min CZE separation with indirect UV detection at 214 nm. The addition of 0.1% (v/v) formaldehyde to the sample solution stabilizes dithionite and sulfite as HOCH2SO2â and HOCH2SO3â anions. The procedure was applied for the determination of dithionite and its decomposition products sulfite, sulfate and thiosulfate in commercial formulations of bleaching agents. Dithionite was found to be the major component of the commercial formulations in concentrations between 30.80 and 33.30% (w/w). As anticipated, sulfite, sulfate and thiosulfate were found to be present as decomposition or by-products in the commercial formulations at concentrations of 14.30-14.80, 5.20-5.70 and 0.30-0.40% (w/w), respectively. The results were found to be in good agreement with those of polarographic and spectrophotometric determinations.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Leandro M. de Carvalho, Georg Schwedt,