Highly sensitive fluorescence detection with Hg-lamp and photon counter in microchip capillary electrophoresis

摘要

A microchip capillary electrophoresis system with highly sensitive fluorescence detection is reported.The system was successfully constructed using an inverted fluorescence microscope,a highly sensitive photon counter,a photomultiplier tube (PMT) and a capillary electrophoresis microchip.This system can be applied to the fluorescence detection with various wavelengths (300-600 nm).Different fluorescence reagents require different excitation wavelengths.The wavelengths of UV light (300-385 nm),blue light (450-480 nm) and green light (530-550 nm) are employed to excite Titan yellow,fluorescence-5-isothiocyanate (FITC) and Rhodamine 6G,respectively.The detection limit (S/N=3) of FITC is 7 x 10~(-10) M,which is 2-3 orders of magnitude lower than that obtained with the lamp-based fluorescence and PMT detection system and approaches the data gained by the laser-induced fluorescence detection.The linear relationship is excellent within the range of concentration 1.3 x 10~(-9) to 6.5 x 10~(-8) M FITC.It offers a new method to widen the application of the lamp-based fluorescence detection.