DETERMINATION OF SULFIDE IN THE LEATHER INDUSTRY BY CAPILLARY ELECTROPHORESIS

Capillary electrophoresis (CE) was investigated for the determination of sulfide in effluents and waste water samples from the leather indus try. A 10 mM sodium sulfate electrolyte at pH 10.5 was used and a quat ernary ammonium hydroxide was added for the reversal of the electroosm otic flow (EOF). The linearity, separation efficiency and the effects of pH, concentration of the EOF modifier and the capillary dimensions were investigated. Direct UV detection at 229 nm provided the best spe cificity and also the best sensitivity, The limits of detection were 4 1 and 10 mu g of S2-/l using a 75- and a 100-mu m I.D. capillary, resp ectively. The reproducibility was considerably improved by using the i nternal standard technique. Molybdate, iodide and biphthalate may be u sed as internal standards. Spiking of real samples gave recoveries bet ween 102 and 111%. The CE method presented here was compared with the classical methods and it was concluded that it may be a good alternati ve for determining sulfide in difficult samples.