Determination of 6 antiestrogens in fish tissues by ultra performance liquid chromatography-tandem mass spectrometry

A comprehensive analytical method based on ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed for the simultaneous determination of 6 antiestrogens (toremifene, clomiphene, tamoxifen, raloxifene, anastrozole and letrozole) in fish muscle and liver. The multi-reaction monitoring mode was employed for the determination. The homogeneous fish tissue samples were ultrasonically extracted with acetonitrile, and then the supernatants were diluted by water. The target compounds were concentrated and purified by a mixed-mode cationic-exchanger (MCX) cartridge, and then separated on an ACQUITY UPLC (TM) BEH C18 column (100 mm x 2.1 mm, 1.7 mu m) using a binary mobile phase gradient with water containing 0.1% formic acid and acetonitrile. The limits of quantification (LOQ, S/N = 10) of the 6 antiestrogens were 0.1 - 0.3 mu g/kg in muscle and liver samples. The average recoveries of target compounds (spiked at four concentration levels) based on internal standard calibration were in the range of 84.9% - 112.2% with the relative standard deviations of 0.9% - 14.3%. This method can be applied to the trace analysis of target drugs in fish muscle and liver samples.