MODIFICATION OF A TUNABLE UV-VISIBLE CAPILLARY ELECTROPHORESIS DETECTOR FOR SIMULTANEOUS ABSORBENCY AND FLUORESCENCE DETECTION - PROFILING OF BODY-FLUIDS FOR DRUGS AND ENDOGENOUS COMPOUNDS

Using fused-silica optical fibres for fluorescence light collection an d bandpass filters for selection of emission wavelengths, a capillary electrophoresis detection cell of a conventional, tunable UV-Vis absor bance detector was adapted for simultaneous fluorescence (at selected emission wavelength) and absorbance (at selected excitation wavelength ) detection. Detector performance is demonstrated with the monitoring of underivatized fluorescent compounds in body fluids by micellar elec trokinetic capillary chromatography with direct sample injection. Comp ared with UV absorption detection, fluorescence detection is shown to provide increased selectivity and for selected compounds also up to te nfold higher sensitivity. Examples studied include screening for urina ry indole derivatives (tryptophan, 5-hydroxytryptophan, tyrosine, 3-in doxyl sulfate and 5-hydroxyindole-3-acetic acid) and catecholamine met abolites (homovanillic acid and vanillylmandelic acid) and the monitor ing of naproxen in serum, quinidine in serum and urine and of salicyla te and its metabolites in serum and urine.