On-Line Dialysis Coupled to a Capillary Electrophoresis System for Determination of Small Anions

Abstract

On-line dialysis performed in a flow injection analysis (FIA) system has been integrated with a capillary electrophoresis (CE) system via a specially designed interface. Samples are continuously pumped into a dialysis unit and the outgoing acceptor stream containing the analytes is allowed to fill a rotary injector in the FIA part of the system. A discrete, representative volume of the acceptor stream is injected into an electrolyte stream which continuously passes through the FIA−CE interface into which the end of a capillary has been inserted. An infinitesimal fraction of the injected acceptor plug is introduced electrokinetically when it passes the end of the capillary. Multiple sample injections are possible in one electrophoretic run, and the entire analytical procedure can easily be mechanized. The repeatability is in the range 1.6−3.3% (n = 7). A wide range of real samples with complicated matrices (milk, juice, slurry, liquors from pulp and paper industry) was successfully analyzed without any off-line pretreatment using the fully mechanized system.