SOLUTION-PHASE IMMUNOASSAY FOR DETERMINATION OF CORTISOL IN SERUM BY CAPILLARY ELECTROPHORESIS

We describe a competitive solution-phase immunoassay for serum cortiso l determination that involves capillary electrophoresis (CE) combined with laser-induced fluorescence for separation and quantification. A p olyclonal antibody preparation and fluorescein-labeled cortisol are us ed as assay reagents. 8-Anilino-1-naphthalenesulfonic acid was added t o the serum sample during the assay to promote the release of cortisol from endogeneous binding proteins. Conditions for the rapid separatio n of free and bound labeled antigen by CE were developed. Aspects of a ssay performance are evaluated in this report. The resulting assay pro tocol allows for the analysis of serum samples without extraction or o ther sample preparation steps.