CAPILLARY ZONE ELECTROPHORESIS OF INORGANIC ANIONS WITH CONDUCTIVITY DETECTION

A carrier electrolyte system for capillary zone electrophoresis (CZE) resolving chloride, bromide, iodide, fluoride, nitrite, nitrate, sulfa te, and phosphate in a hydrodynamically closed separation compartment is described. The carrier electrolyte combines the effects of pH, poly vinylpyrrolidone (PVP) and the counterionic constituent on the effecti ve mobilities of the anions. In 300 mu m ID capillary tubes made of fl uorinated ethylene-propylene copolymer (FEP), and with detection of an alytes with the aid of an alternating current conductivity detector, d etection limits in the range of 3-10 ppb could be achieved for 200 nL sample volumes. The separation efficiencies were in the range of 1.5-2 .5 x 10(5) theoretical plates per meter for an adequate sample load. T he reproducibility was evaluated for two concentration levels. For con centrations close to the limits of quantitation (50-120 ppb), the RSD values ranged from 1.5-12.6%, with the highest scatter for fluoride an d phosphate. The RSD values were in the range of 0.4-1.5% for 300-1200 ppb concentrations of the anions. Typical analysis times were 2-5 min , depending on the anion species. A series of water samples (drinking, river, rain) was used to assess the practical applicability of the CZ E method. The method is a suitable alternative for the determination o f both anionic macro- and microconstituents in water with a good overa ll selectivity.