CAPILLARY-ELECTROPHORESIS WITH LASER-INDUCED NATIVE FLUORESCENCE DETECTION FOR PROFILING BODY-FLUIDS

Laser-induced native fluorescence detection with a KrF excimer laser ( lambda=248 nm) was used to investigate the capillary electrophoretic ( CE) profiles of human urine, saliva and serum without the need for sam ple derivatization. All separations were carried out in sodium phospha te and/or sodium tetraborate buffers at alkaline pH in a 50-mu m I.D. capillary. Sodium dodecyl sulfate was added to the buffer for micellar electrokinetic chromatography (MEKC) analysis of human urine. Althoug h inherently a pulsed source, the KrF excimer laser was operated at a high pulse repetition rate of 553, 1001 or 2009 Hz to simulate a conti nuous wave excitation source. Detection limits were found to vary with pulse rate, as expected, in proportion to average excitation power. T he following detection limits (3 sigma) were determined in free soluti on CE: tryptophan, 4 nM; conalbumin, 10 nM; alpha-lactalbumin, 30 nM. Detection limits for indole-based compounds and catecholamine urinary metabolites under MEKC separation conditions were in the range 7-170 n M. (C) 1998 Elsevier Science BN. All rights reserved.