CAPILLARY ELECTROPHORESIS APPLIED TO THE DETERMINATION OF SOME SELENOCOMPOUNDS

Selenium is well known for its both toxic and beneficial effects on li ving organisms. The toxicity is closely correlated with the form in wh ich selenium is present. The need for new methods for the speciation o f this element led to the study of analytical parameters applicable to the determination of selenite, selenate, selenocystine and selenometh ionine by capillary electrophoresis. The separation is achieved in a c hromate buffer with trimethyltetradecylammonium hydroxide as electroos motic flow modifier. Detection limits are ca 10 mu g 1(-1) for inorgan ic species and 300 mu g 1(-1) for selenoamino acids. Interferences by other inorganic ions were studied and applicable to the determination of selenium in a thermal water led to results in good agreement with t hose given by differential-pulse cathodic stripping voltammetry.