SPECIATION OF SELENIUM AND ARSENIC COMPOUNDS BY CAPILLARY ELECTROPHORESIS WITH HYDRODYNAMICALLY MODIFIED ELECTROOSMOTIC FLOW AND ONLINE REDUCTION OF SELENIUM(VI) TO SELENIUM(IV) WITH HYDRIDE GENERATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION

Capillary electrophoresis (CE) with hydride generation inductively cou pled plasma mass spectrometry was used to determine four arsenicals an d two selenium species, Selenate (Se-VI) was reduced on-line to seleni te (Se-IV) by mixing the CE effluent with concentrated HCl, A micropor ous PTFE tube was used as a gas-liquid separator to eliminate the (ArC l)-Ar-40-Cl-37 and (ArCl)-Ar-40-Cl-35 interference from Se-77 and As-7 5, respectively, The direction of the electroosmotic flow during CE wa s reversed with hydrodynamic pressure, which allowed increased freedom of buffer choice, For conventional pressure injection, method detecti on limits for Se-IV and Se-VI based on seven replicate injections were 10 and 24 pg, respectively, Recoveries of Se-IV and Se-VI in drinking mater were measured.