FEASIBILITY STUDIES FOR SIMULTANEOUS IMMUNOCHEMICAL MULTIANALYTE DRUGASSAY BY CAPILLARY ELECTROPHORESIS WITH LASER-INDUCED FLUORESCENCE

We present a method for the simultaneous quantification of multiple dr ug analytes in urine, based on combining immunochemical binding with c apillary electrophoretic separation. Two fluorescent drug-cyanine (Cy) dye conjugates were prepared as competing species for the immunoassay . Morphine was derivatized with Cy5 (lambda(max) = 652 nm, epsilon = 2 15 000 mol(-1)cm(-1)), phencyclidine (PCP) with Gy5.5 (lambda(max) = 6 75 nm, epsilon = 200 000 mol(-1)cm(-1)L). The high-efficiency resolvin g power of the capillary electrophoresis system (20 mu m x 27 cm colum n) separated the individual labeled drugs, and the antigen-antibody co mplexes were detected by laser-induced fluorescence (laser: 10 mW He-N e at 632.8 nm) with Cy5 diacid as internal standard. Simultaneous comp etitive immunoassay of morphine and PCP in urine showed that the free labeled-drug peak areas were proportional to the concentrations of the drug species present in the urine sample. This immunoassay can be per formed routinely and reproducibly in <5 min with analytical detection limits of 4 nmol/L for PCP and 40 nmol/L for morphine.