Determination of estrogen-like compounds in fish liver tissue by solid-phase extraction-gas chromatography-mass spectrometry

An analytical procedure for the simultaneous determination of eight estrogen-like compounds (nonylphenol (NP), 4-tert-octylphenol(OP), bisphenol A (BPA), diethylstilbestrol (DES), estrone (El), 17β-estradiol (E2), 17α-ethinylestradiol (EE2) and estriol (E3)) in liver of fish by solid-phase extraction (SPE) and ga s chromatography/mass spectrometry (GC-MS) has been developed. Liver tissue samples added with 17β-estradiol-d4 (E2-d4, surrogate standard) are extracted by acetonitrile under ultrasonication and the lipid in the sample extract is eliminated by partitioning between hexane and acetonitrile. After Oasis HLB SPE column clean-up, the sample extract is derivatized with N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA). The derivatives of tar get compounds in the samples are determined by GC-MS in the s elected ion monitoring (SIM) mode. The linearities range from 0. 005 to 0.8 mgL^-1 for all target compounds. The average recoveries are 72.5±12.6% to 110.2±12.2% at 0.5 μg kg^-1, 5 μg kg^-1 and 20 μg kg^-1 spiked levels of target compounds. And the limits of quantification (LOQ) are 0.15 to 0.8 ngg^-1 (R.S.D. 5.6% to 12.8%). The method is simple with good reproducibility and selectivity, an d high sensitivity. The application of this method is further demonstrated by analyzing various real samples from local supermarkets.