Simultaneous Determination of Steroid Endocrine Disrupting Chemicals in Water by Solid Phase Extraction-Derivatization- Gas Chromatographic-Mass Spectrometry

An analytical method for the simultaneous determination of steroid endocrine disrupting chemicals, such as estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethynylestradoil (EE2), in water was developed by solid phase extraction (SPE), derivatization, and gas chromatography-mass spectrometry. To explain the necessity of heating and catalyst in previous papers where N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) or N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) was used as derivatization reagent, the derivatization condition and effect of BSTFA and MSTFA were studied. Based on the results, BSTFA was applied to derivatize steroids in waters without heating and catalyst. By optimizing SPE parameters, the best recoveries of steroids were obtained when water pH value was adjusted to 4.5 and Oasis HLB cartridge was used; moreover, 10 mL acetone was efficient in eluting steroids from SPE cartridges. Under the optimal conditions, linear detection range was 1-500 ng L−1 for E1 and E2, whereas it was 5-500 ng L−1 for EE2 and E3. The correlation coefficient (R2) was above 0.98 for all the analytes, with the limit of detection (LOD) and the limit of quantification (LOQ) of 0.1-1.3 ng L−1 and 0.3-4.2 ng L−1, respectively. The proposed method was further verified by performing spiking experiments on Dianchi Lake water at three spike levels (5, 50 and 300 ng L−1), with good recoveries (83.8%-94.7%) and RSD (3.2%-9.1%, n = 6) for all the target compounds. The established method was successfully applied to determine steroids in water samples from Dianchi Lake, Green Lake, and effluent of Kunming fifth sewage treatment plant.