Chemiluminescence detection of nine corticosteroids in liver

A method for the determination of nine corticosteroids in bovine liver was developed. The liquid-liquid extraction method consisted in the addition of sodium hydroxide to the tissue sample followed by extraction with ethyl acetate. After centrifugation, the extract was evaporated to dryness and the residue redissolved in acetonitrile. The removal of fats was performed with n-hexane and the acetonitrile layer was evaporated. Afterwards, analysis of the extracts was performed using high-performance liquid chromatography with chemiluminescence detection employing luminol as reagent. The recovery curves, performed at five spiking levels (different for each corticosteroid), showed that recoveries of at least 70.5% could be obtained from liver. The chemiluminescence detection gave satisfactory results with respect to sensitivity, and the LOQ ranged from 0.13 ppb for prednisolone to 8.40 ppb for betamethasone. The maximum mean RSD was 4.8% and 7.3% for intra- and inter-day assay, respectively.