No abstract

This paper presents principle and first results of a novel competitive binding immunoassay for monitoring of theophylline in human serum. The assay is based upon short time incubation of a mixture of antiserum, containing the antibody raised against theophylline, fluorescein labelled theophylline (tracer) and serum prior to injection of a few nanoliter of this mixture onto a fused-silica capillary for subsequent separation and analysis of free tracer and the antibody-tracer-complex by micellar electrokinetic capillary chromatography with laser induced fluorescence detection. Quantitation based upon multi-level calibration using the height of the peak produced by the free tracer is shown to provide theophylline serum levels which are in agreement with those obtained by a commercial fluorescence polarization immunoassay and with those determined by micellar elektrokinetic capillary chromatography with direct serum injection and on-column UV absorption detection.

No abstract

This paper characterizes competitive binding, electrokinetic capillary-based immunoassays for various drugs in human serum using reagents which were commercialized for fluorescence polarization immunoassays. After incubation of serum with the reactants, a small aliquot of the mixture is applied onto a fused-silica capillary and tracers (fluorescein-labeled drugs) and the antibody-tracer complexes are separated and analyzed by micellar electrokinetic capillary chromatography with on-column laser-induced fluorescence detection. Examples studied include serum assays for theophylline, ethosuximide, paracetamol, salicylate and quinidine. With these assays, concentration-dependent peaks produced by the free tracers or the antibody-tracer complexes serve as the basis for quantitation. The sizes of the peaks produced are shown to be dependent on the applied power and the proportions of the reactants and serum employed. The separation medium permits effective characterization of tracers and antibody selectivities. Based on the high selectivity of the antibodies employed, the feasibility of the simultaneous performance of different immunoassays is demonstrated. For capillaries of 50 microns internal diameter (ID), separations are best performed at electric fields < 500 V/cm, this resulting in electrokinetic analyses within 4 to 10 min (capillaries of 20 to 50 cm effective length).

No abstract