WAVELENGTH-RESOLVED FLUORESCENCE DETECTION IN CAPILLARY ELECTROPHORESIS

A multichannel laser-induced fluorescence detector for capillary elect rophoresis is described. The detection system combines yoctomole limit s of detection with the simultaneous acquisition of entire fluorescenc e emission spectra. An Ar/Kr mixed-gas ion laser provides great flexib ility in excitation wavelengths, and a holographic grating and charge- coupled device detector combination allows a 500-mn spectral window to be acquired with 2-nm resolution. The limits of detection are 5 x 10( -14) M or 80 molecules for sulforhodamine 101 and 1.5 x 10(-13) M or 2 20 molecules for fluorescein in a 50 mu m i.d. capillary, An electroph erogram of a mixture of amino acids derivatized with both Bodipy 503/5 12 C-3 and Bodipy 576/589 C-3 demonstrates that the analytes can be di fferentiated on the basis of both emission characteristics and migrati on times, With the use of organic modifiers and other complex separati on media, the spectral background increases as discrete spectral featu res appear; the wavelength-resolved backgrounds of a variety of common CE separation conditions are presented.