FLOW-INJECTION ANALYSIS IN THE CAPILLARY FORMAT USING ELECTROOSMOTIC PUMPING

Electroosmotic flow induced by an electric field in a 75-mum bore fused-silica capillary is used as the pumping mechanism for flow-injection analysis (FIA). Injection of a sample into a reagent stream containing a carrier electrolyte or sequential injection of contiguous reagent, sample and reagent segments into a carrier electrolyte are accomplished hydrostatically. Colorimetric detection is performed by an optical absorbance detector using the diameter of the capillary as the optical path. Typical peak area precision is better than 3% in relative standard deviation for sample volumes less-than-or-equal-to 20 nl. The potential of capillary format electroosmotically driven FIA and related techniques is discussed.