Analysis of urinary drugs of abuse by a multianalyte capillary electrophoretic immunoassay

This paper characterizes a novel multianalyte competitive binding, electrok inetic capillary-based immunoassay for urinary methadone, opiates, benzoyle cgonine (cocaine metabolite) and amphetamines. After incubation of 25 mu l urine with the reactants for several minutes in the presence of an internal standard, a small aliquot of the mixture is applied onto a fused-silica ca pillary and the unbound fluorescein labelled drug tracers are monitored by capillary electrophoresis with on-column laser induced fluorescence detecti on. The multianalyte assay is shown to be rapid, simple, quantitative, capa ble of recognizing urinary drug concentrations greater than or equal to 30 ng/ml and suitable for screening of patient urines. Data are demonstrated t o compare well with those obtained by routine screening methods based on en zyme multiplied immunoassay techniques and fluorescence polarization immuno assays. The electrokinetic capillary assay has been validated via analysis of external quality control urines and confirmation analysis of patient uri nes using GC-MS. (C) 1999 Elsevier Science B.V. All rights reserved.