Development and application of a UHPLC-MS/MS method for the simultaneous determination of 17 steroidal hormones in equine serum.

A new, fast and simple analytical method that is able to identify and quantify simultaneously 17 steroid hormones and metabolites (pregnenolone, 17-OH-pregnenolone, progesterone, 17-OH-progesterone, androsterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, cortisol, corticosterone, aldosterone, 11-deoxycortisol, 11-deoxycorticosterone, dihydrotestosterone, estrone and estradiol) has been developed in equine serum using the ultrahigh- performance liquid chromatography-tandem mass spectrometry technique. A total of 400 μl of sample was deproteinized with 1000 μl of acetonitrile, evaporated, restored with 50 μl of a solution of 25% methanol and injected in ultrahigh- performance liquid chromatography-tandem mass spectrometry triple quadrupole. The recovery percentage obtained by spiking the matrix at two different concentrations with a standard mixture of steroid hormones was in all cases higher than 85.60% and with the percentage of coefficient of variation lower than 8.37%. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.9922-0.9986, and the limits of detection and limits of quantification were in the range of 0.002-2 and 0.0055-5.5 ngml-1, respectively. The detected limit of quantification for testosterone (i.e. 50pgml-1) is twofold lowerwith respect to its threshold admitted in geldings plasma (100pgml-1 free testosterone). The high sensitivity and the quantitative aspect of the method permitted to detect most of the steroids in equine serum. Once validated, the method was used to quantify 17 steroid hormones in mare, stallion and gelding serum samples. The main steroids detected were corticosterone (range 37.25-51.26 ngml-1) and cortisol (range 32.57-52.24 ngml-1), followed by 17-OH-pregnenolone, dihydrotestosterone and pregnenolone. [ABSTRACT FROM AUTHOR]