DETECTION AND QUANTIFICATION OF CAPILLARY ELECTROPHORESIS ZONES BY FLUORESCENCE MICROSCOPY

A fluorescence detector for capillary electrophoresis was built using an epillumination fluorescence microscope equipped with a 50-W mercury lamp and a photodiode. The performance of the detector was tested with riboflavin and fluorescamine-derivatized amino acids and amphetamine. We compared fluorite and conventional glass objectives and found that, by using a 25-μm I.D. capillary and a fluorite objective, an improvement in fluorescence detection by a factor of 56 can be achieved. A detection level of 500 amol for riboflavin was reached (using on-column detection). This sensitivity was at least comparable to that reported for other capillary electrophoresis systems using on-column non-coherent light fluorescence detectors. The potential and advantages of using a fluorescence microscope for capillary electrophoresis applications are discussed. © 1990.