Determination of natural corticosteroids in urine samples from sportsmen

A method for the determination of natural corticosteroids (cortisone, cortisol, 5β-dihydrocortisone, 5β-dihydrocortisol, tetrahydrocortisone and tetrahydrocortisol) found in the urine of sportsmen, was developed using a capillary gas chromatography–mass spectrometry ion trap system. 17α-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.