Determination of Bisphenol A and Nonylphenol in Infant Formula Milk Powder by UPLC-MS/MS

An accurate qualitative and quantitative method was established for determination of bisphenol A and nonylphenol in infant formula milk powder by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).Infant formula milk powder was dissolved in water,extracted by acetonitrile,online capture technology can eliminate background effects in mobile phase. Gradient elution was carried out on C₁₈ column with methanol-0.1% ammonia solution as mobile phase,then the identification and quantitation of bisphenol A and nonylphenol was performed by MS/MS in negative electrospray ionization(ESI^-)and multiple reaction monitoring(MRM)mode. The results showed that there was a good linear relationship in the range of 1~2000 ng/mL. The correlation coefficient was greater than 0.999.The detection limits of BPA and NP in this method were 0.1 μg/kg. Three levels of 1,10 and 100 μg/kg were added to different infant formula milk powder. The average recovery of the results was 89.5%~102.8%,and the relative standard deviation was from 1.3% to 4.8%. The method had high sensitivity and accuracy. 200 samples of infant formula milk powder purchased from the market were determined. bisphenol A content was 0.1~30.0 μg/kg and nonylphenol content was 1.1~105 μg/kg,which was suitable for quantitative determination of bisphenol A and nonylphenol in infant formula milk powder.