Estrogenic chemicals, particularly the synthetic contraceptive steroid 17α-ethynylestrodiol (EE2) and natural steroid estrone (El) and 17β-estradiol (E2), have attracted a great deal of scientific and public attention during recent years due to their occurrence in surface waters and sewage treatment plant effluents and their potential adverse effects on the development and reproduction of fish, wildlife and even humans.Concentrations of estrogenic steroids have usually been detected at the low-ng/L levels using GC-MS after silylation.