SIGNAL ENHANCEMENT BY ON-COLUMN FLUOROMETRIC DETECTION IN MICROCOLUMN LIQUID-CHROMATOGRAPHY WITH CYCLODEXTRIN-BONDED STATIONARY PHASES

Fluorescence signals of dansyl amino acids were enhanced by on-column detection in microcolumn liquid chromatography with cyclodextrin-bonded silica gel as the stationary phase. The flow cell of the fluorimetric detector was prepared from 0.32 mm ID fused-silica tubing packed with the same material as for the separation column. In the on-column fluorimetric detection the peak height of the analytes increased with increasing capacity factor owing to the focussing and environmental effects of the stationary phase. The detection limits achieved by the on-column detection were 6 to 11 times better than those achieved by using an empty flow cell.