[Simultaneous determination of three estrogens in feed by solid phase extraction-ultra performance liquid...

A method was developed for the simultaneous determination of three estrogens (17β-estradiol, estradiol benzoate, estradiol valerate) in feed by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). After the sample was extracted by acetonitrile and cleaned-up on a Heaion C18 solid phase extraction (SPE) column, the three estrogens were separated by an ACQUITY UPLC BEH C18 column (50 mm x 2.1 mm, 1.7 μm) with gradient elution using acetonitrile and 0.1% ammonia solution as mobile phases and finally confirmed and quantified in multiple reaction monitoring (MRM) mode. The internal standard calibration curves were used for the quantification. The results showed that all the estrogens were determined with excellent linear relationships from 10 μg/L to 200 μg/L for 17β-estradiol and estradiol valerate, and from 5 μg/L to 200 μg/L for estradiol benzoate. The correlation coefficients (r) of the three estrogens were not lower than 0. 996. The limits of detection for 17β-estradiol, estradiol benzoate and estradiol valerate were 7 μg/kg, 5 μg/kg and 7 μg/kg, respectively. The average recoveries were 96.5%-102.0%. The results demonstrated that the developed method can simultaneously determine the three estro- gens in feed with advantages of simple pretreatment, rapid analysis, low limit of detection and high accuracy.