A Transparent Flow Gating Interface for the Coupling of Microcolumn LC with CZE in a Comprehensive Two-Dimensional System

Abstract

A new interface for the coupling of microcolumn high-performance liquid chromatography (micro-HPLC) with capillary zone electrophoresis (CZE) is presented. The new interface is based on the original flow gated design developed in this laboratory but is now made from a clear plastic which allows for the direct observation and routine manipulation of the micro-HPLC and CZE capillaries. As with the original design, a transverse flow of CZE buffer controls analyte injection onto the CZE capillary. To evaluate the reproducibility of the interface, 400 consecutive CZE separations of a mixture of fluorescein 5-isothiocyanate (FITC)-labeled phenylalanine and glutamic acid are performed over a 2 h period. The percent relative standard deviations (% RSD) of the peak height, peak area, and migration times of 400 runs of FITC-phenylalanine are 2.5, 3, and 0.07%, respectively, and of FITC-glutamic acid are 2.5, 3.5, and 0.07%, respectively. The % RSDs of the peak height, peak area, and migration time were reduced to 0...