CAPILLARY ELECTROPHORESIS-BASED IMMUNOASSAY FOR CORTISOL IN SERUM

A competitive immunoassay for cortisol based on capillary electrophore sis (CE) and laser-induced fluorescence is described. The work involve d the production of assay reagents and the development of separation c onditions allowing for routine analysis of serum samples. Fluorescein- labeled cortisol was synthesized and purified. Fab fragments were prod uced from mouse monoclonal anticortisol antibody and purified using a POROS cation exchange chromatography column. After incubation of these reagents with serum, free and bound labeled antigen were separated by CE with high reproducibility. No prior sample cleanup of the serum sa mples was necessary. Serum calibration curves were established and use d for the quantitation of cortisol in serum. The results demonstrate f easibility for a cortisol assay based on CE operating directly on seru m samples.