Solid-state extraction of cortisol from plasma or serum for liquid chromatography.

Solid-state extraction of plasma or serum offers significant advantages over traditional liquid-liquid methods in cortisol determinations by liquid chromatography (HPLC). Sample preparation is facilitated and HPLC column contamination is minimized. Extract yield from the solid-state columns is enhanced by sample pretreatment with methanol. Cortisol values by solid-state extraction/HPLC correlate well (r = 0.92) with those from a commercial radioimmunoassay procedure.

High-performance liquid chromatography and radioimmunoassay of rat plasma corticosterone.

Problems inherent in corticosterone radioimmunoassay (RIA) led to consideration of alternative methods. A high-performance liquid chromatography (HPLC) procedure was evaluated that separated and quantitated dichloromethane-extracted corticosterone by reverse-phase chromatography. The results were correlated (r = 0.92) with an RIA procedure. The HPLC recovered nearly 100% of corticosterone added to rat plasma and had excellent reproducibility. In addition, chromatogram profiles of dichloromethane-soluble components obtained from rat plasma, derived from drug effect studies, could have value for characterizing response patterns. Without automated sample injection equipment, HPLC is more appropriately applied in monitoring RIA results than in processing large numbers of samples.