Sulfur speciation by capillary zone electrophoresis: conditions for sulfite stabilization and determination in the presence of sulfate, thiosulfate and peroxodisulfate

Capillary zone electrophoresis (CZE) was used for the separation of the sul fur species SO32-, SO42-,S2O32- and S2O82- Using an electrolyte system with 9.5 mmol L-1 potassium chromate as UV-absorbing probe and 1 mmol L-1 dieth ylenetriamine (DETA) as electroosmotic Row modifier, various possibilities for the stabilization of sulfite and electrophoretic separation of the sulf ur anions were investigated. By adding 5% propanol as a stabilizer to both the working electrolyte and the sample solution, a good stabilization for s ulfite and a separation of the sulfur anions in a short analysis time (4 mi n) was achieved. The advantages by using propanol instead of other stabiliz ers often used in analytical techniques are discussed. The electrophoretic separation of the sulfur anions was optimized with respect to the pH of the working electrolyte and concentration of the electroosmotic flow modifier (DETA). The detection limits achieved for SO32-, SO42-, S2O32- and S2O82- w ere 0.35, 0.25; 0.78 and 0.80 mg L-1, respectively.