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.