Simultaneous Determination of Estrogen Drugs in Feeds by Liquid Chromatography-Tandem Mass Spectrometry with Isotope Dilution

XUE Yi;ZHANG Yue;LV Yan;WU Yin-Liang;The Center for Animal Disease Control and Prevention;The Ningbo Academy of Agricultural Sciences;

The Center for Animal Disease Control and Prevention%The Ningbo Academy of Agricultural Sciences

Estrogen drugs;;Feed;;Isotope dilution;;Liquid chromatography tandem mass spectrometry

A method was developed for determining eight estrogen drugs in feeds using liquid chromatography tandem mass spectrometry with isotope dilution. Samples were extracted with acetonitrile and centrifuged. The extract was dried under nitrogen and the residue was redissolved with ethyl acetate. Then, the samples were cleaned up by sodium carbonate solution with a liquid-liquid extraction method. After clean-up, the samples were analyzed by LC-MS/MS on an Acquity HSS T3 column with a mixture of water and acetonitrile as mobile phase under gradient elution conditions. The analytes were determined by negative electrospray ionization with multiple reaction monitoring(MRM). Internal standard method was used to quantify the analytes. There is a good linear correlation between the peak areas and concentration of eight estrogen drugs in the range of 1.0 μg/L to 200 μg/L. The eight estrogen drugs were measured in fortified feeds at 1.0~50 μg/kg levels. Average recoveries were in the range of 97.5%~106%. The limit of detection(LOD) and limit of quantification(LOQ) was 0.15~0.30 μg/kg and 0.50~1.0 μg/kg, respectively. The method is demonstrated to be suitable for the determination of the eight estrogen drugs in feeds.