Abstract
A sensitive and accurate method for determination of 17 endogenous and exogenous steroid hormones in Antarctic krill was developed. The method utilized UHPLC-MS in electrospray ionization mode (ESI). Samples were prepared by alkaline hydrolysis; sequential vortex extraction with ethyl acetate, methanol and acetonitrile; followed by a QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) clean-up method. The system suitability tests including theoretical plate number, resolution, repeatability, tailing factor proved the system's resolution and reproducibility that can meet the requirements of sample analysis. The developed method resulted in satisfactory recoveries that varied from 75.4%-110.6% and relative standard deviations (RSDs) that ranged from 3.1%-10.5%. The ranges of the limits of detection (LODs) and the limits of quantitation (LOQs) were 2-30 ng kg-1 and 10-100 ng kg-1, respectively. 14 hormones including cortisone, aldosterone, testosterone propionate, estriol, megestrol acetate, cortisone acetate, dexamethasone, testosterone, hydroxyprogesterone, nandrolone, prednisolone, cortisol, progesterone and estradiol were found in Antarctic krill. Other 3 hormones (Diethylstilbestrol, norethisterone and androsterone) were not detected. The levels of exogenous steroid hormones were much greater than those of endogenous steroid hormones, and the levels of exogenous glucocorticoids were much greater than those of exogenous sex hormones. The changes of hormones in different sex and maturity stages were also explored. Endogenous hormones might regulate the reproductive and development of Antarctic krill. The detected exogenous hormones suggests the potential for hormonal contamination in Antarctic waters that can affect organisms even affect human beings by food chain.