Screening for urinary amphetamine and analogs by capillary electrophoreticimmunoassays and confirmation by capillary electrophoresis with on-column multiwavelength absorbance detection

This paper characterizes competitive binding, electrokinetic capillary-base d immunoassays for screening of urinary amphetamine (A) and analogs using r eagents which were commercialized far a fluorescence polarization immunoass ay (FPIA), After incubation of 25 mu L urine with the reactants, a small al iquot of the mixture is applied onto a fused-silica capillary and unbound f luorescein-labeled tracer compounds are monitored by capillary electrophore sis with on-column laser-induced fluorescence detection. Configurations in presence and absence of micelles were investigated and found to be capable of recognizing urinary D-(+)-amphetamine at concentrations > about 80 ng/mL . Similar responses were obtained for racemic methamphetamine (MA) and 3,4- methylenedioxymethamphetamine (MDMA). The electrokinetic immunoassay data s uggest that the FPIA. reagent kit includes two immunoassay systems (two ant ibodies and two tracer molecules), one that recognizes MA and MDMA, and one that is geared towards monitoring of A. For confirmation analysis of urina ry amphetamines and ephedrines, capillary electrophoresis in a pH 9.2 buffe r and multiwavelength UV detection was employed. The suitability of the ele ctrokinetic methods for screening and confirmation is demonstrated via anal ysis of patient and external quality control urines.