Improved method for analyzing estrogens in water by liquid chromatography–electrospray mass spectrometry

An improved LC–electrospray ionization MS method was established for four estrogens (17β-estradiol (E2), estriol (E3), estrone (E1), and ethynyl estradiol (EE)) in environmental water. Almost complete separation of all estrogens was achieved on a phenyl column with methanol/water as the mobile phase. Quantification was achieved in the negative ionization mode using selected ion monitoring. The instrumental detection limits were 20–30 ng/l for the four analytes. In Milli-Q spiked water, the recoveries of the four estrogens were 72–81%, which was similar to those found for river water spiked with the corresponding deuterated estrogens. The detection limits for the four estrogens in river water were 0.1–0.2 ng/l. The method was used to detect residual estrogens in the Tonghui River, which receives water from a municipal sewage treatment plant in Beijing; E1 (1.1 ng/l) and E2 (0.2 ng/l) were detected.