Simultaneous Determination of Ten Estrogens and their Metabolites in Waters by Improved Two-Step SPE Followed by LC-MS

Ten highly potent estrogens including estrone (E-1), 17 beta-estradiol (E-2), estriol (E-3), 4-hydroxyestrone (4-OHE1), 2-hydroxyestradiol (2-OHE2), 16 alpha-hydroxyestrone (16 alpha-OHE1), 2-methoxyestrone (2-MeO-E-1), 2-methoxyestradiol (2-MeO-E-2), diethylstilbestrol (DES), 17 alpha-ethynylestradiol (EE2) were identified and quantified by solid-phase extraction followed by liquid chromatography-mass spectrometry. An improved two-step SPE process was employed in this work. C18 cartridge was used for both enrichment of all target estrogens and retention of some nonpolar impurities, and then a polar florisil cartridge was subsequently used to separate the interested estrogens from the polar impurities. After this pretreatment for water samples, the results showed clean chromatograms without interference from matrix effects. Besides, this method was accurate (recovery percentages between 70.4 and 106.8% for river water and 73.4 and 101.3% for raw sewage, except 4-OHE1 and 2-OHE2), and precise (RSD varying between 1.3 and 17.8% for river water and 3.4 and 16.7% for raw sewage). In the optimized condition, this method was used to verify the presence of the target analytes in the Qinghe River and influent of sewage treatment plant in the northwest of Beijing, China. Some estrogens were detected in the river water and sewage water samples at a relatively high concentration. The developed method proved to be effective for analyzing estrogen compounds in complex matrices. Moreover, the achieved results demonstrated that a great concern should be addressed to the potential risk of the presence of estrogens in the aquatic environment.