ABSORPTION DETECTION IN CAPILLARY ELECTROPHORESIS BY FLUORESCENCE ENERGY-TRANSFER

Normally, only highly fluorescent materials can be detected at low concentrations In the small detection volumes typical of capillary electrophoresis In a laser-based fluorometer. We report here the detection of absorbing but nonfluorescing analytes by laser-excited fluorescence. This is possible If the excited analytes transfer their energy to a fluorescent additive In the running buffer to increase the background fluorescence level. Two different fluorophores and four different absorbing analytes were tested in this detection scheme. Concentrations as low as 6 ×10−9 and amounts as small as 4 amol at injection are detectable. The data support a long-range energy-transfer scheme, but the transfer efficiency is much larger than those reported for other donor-acceptor pairs. © 1990, American Chemical Society. All rights reserved.