Abstract: A comprehensive analytical method based on liquid chromatography-electrospray ionization tandem mass spectrometry with negative ionization mode has been developed for measuring alkylphenols (AP) and bisphenol A (BPA) in animal tissues. Samples of animal tissues were extracted by accelerated solvent extraction with dichloromethane. Sample concentration and purification were performed using an OASIS NH2 solid extraction cartridge. The effects of mobile phase and additives on ionization were assessed. The recoveries for the compounds ranged from 88% to 101% and the relative standard deviations were below 15%. The detection limits of the method under multiple-reaction monitoring mode were 0.3, 0.05 and 0.1 μg/kg for BPA, nonylphenol (NP) and octylphenol (OP), respectively. The contents of NP ranging from 0.49 to 55.98 μg/kg were found in 27 real samples of animal tissues from Beijing market. The results indicate that the endocrine disrupting nonylphenol is ubiquitous in food of animal origin. Nonylphenol was found in all fish samples with concentration levels ranging from 9.13 to 55.98 μg/kg.

Key words: alkylpheol, animal tissues , bisphenol A, liquid chromatography-tandem mass spectrometry, accelerated solvent extraction