Comparison of capillary electrophoresis-based immunoassay with fluorescence polarization immunoassay for the immunodetermination of methamphetamine using various methamphetamine antibodies

An accurate and simple immunoassay using capillary electrophoresis (CE) wit h laser-induced fluorescence (LIF) was performed for the detection of metha mphetamine (MA) in urine. The CE-LIF was conducted with an untreated fused- silica column using antiserum and a tracer of fluorescein isothiocyanate (F ITC)-labeled MA. This CE-LIF system was compared with fluorescence polariza tion immunoassay (FPIA) in a TDx analyzer in the photo-check mode using the same FITC-labeled tracer and the same antiserum. Various antibodies, not o nly those prepared by our own immunogens but also those from commercial sou rces, were screened and characterized in both assay systems with regard to sensitivity, precision, and cross-reactivity. Both systems satisfied analyt ical precision and gave similar crossreactivity patterns. However, the CE-L IF-based immunoassay was approximately one order superior to FPIA in sensit ivity, requiring less volume of sample, antiserum, and tracer for the assay . Considering that the FPIA system is well known to be a useful tool for sc reening antibodies and detecting drugs, the CE-LIF-based immunoassay system , which is seemingly more advantageous than the FPIA system, appears to hav e great power for the characterization of antibodies and for the detection of MA in urine.