Gradient elution electrochromatography with a flow-injection analysis interface

A flow-injection analysis-capillary electrochromatography interface is used for gradient elution capillary electrochromatography giving purely electro osmotic flow through the analytical column. Solvent gradients were generate d with a micro-LC system connected to the interface. Injections were carrie d out on-line using an inert rotary LC valve controlled by an electric actu ator. Gradient shape was measured from acetonitrile (5% acetone)-water (50: 50, v/v) to (100:0) in open tubular experiments. When compared to conventio nal instrumentation, peak tailing and peak width increased slightly using t he interface. A test mixture of nine solutes was evaluated in isocratic and gradient elution modes. Using the interface, a gradient of MeCN-water (60: 40) to (90:10) provided baseline separation of all nine solutes in under 18 min with good band spacing. Reproducibility of retention times in eight re plicate injections was found to be better than 2% R.S.D. for all solutes. T his interface also allows use of autoinjectors and dramatically lessens mov ement of the packed column, improving column lifetime. (C) 1998 Elsevier Sc ience B.V. All rights reserved.