OPTIMIZATION OF INJECTION TECHNIQUE IN CAPILLARY ION ELECTROPHORESIS FOR THE DETERMINATION OF TRACE-LEVEL ANIONS IN ENVIRONMENTAL-SAMPLES

Capillary ion electrophoresis (Waters' trade name: Capillary Ion Analysis) offers several advantages compared to ion chromatography for the analysis of ionic solutes, primarily simplicity, matrix independence, and a different separation selectivity. The use of electromigration sample introduction leads to on-capillary enrichment of ionic analytes at the sample-buffer interface, permitting the determination of low ng/ml levels of anions in environmental samples of moderate ionic strength. This injection method allows improved sensitivity compared to hydrostatic injection; and is significantly more rapid than precolumn concentration ion chromatography. The analyte enrichment rate, hence peak response, is strongly dependent upon ionic strength and appropriate measures, such as standard addition or internal standard techniques, must be used to account for differences in standard and sample conductance.