Determination of natural corticosteroids in urine samples from sportsmen.

A method for the determination of natural corticosteroids (cortisone, cortisol, 5beta-dihydrocortisone, 5beta-dihydrocortisol, tetrahydrocortisone and tetrahydrocortisol) found in the urine of sportsmen, was developed using a capillary gas chromatography-mass spectrometry ion trap system. 17alpha-Methyltestosterone was used as an internal standard. The different corticosteroids were determined from the peak area ratios of the [M]; [M-90] and [M-90-90] fragment ions of their methoxime-trimethylsiyl derivatives. Sensitivity (15 ppb), specificity, accuracy (96%) and reproducibility (RSD=4-10%) of the method were demonstrated to be satisfactory for measuring the urinary concentrations of the selected natural corticosteroids.