Abstract: Monodisperse magnetic submicron particles were synthesized by a solvothermal reduction method. A solid phase extraction (SPE) based on the monodisperse magnetic submicron particles and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of bisphenol A (BPA) at trace level in milk has been established. The important parameters that affect the extraction efficiency such as the solution pH, dosage of magnetic submicron particles, nature of elution solution and its volume were optimized. The optimal extraction conditions were as follows: the pH 6.0, the dosage of 3.5 mg magnetic submicron particles and 0.4 mL methanol as elution solution. BPA was analyzed by HPLC-MS/MS in negative ion mode using an Agilent XDB C18 column as analytical column. Under the optimal conditions, the calibration curves showed a good linearity in the BPA concentration range of 1.0~100.0 μg/L. The correlation coefficient was 0.9993. The average recoveries of BPA at three spiked levels ranged from 85.3% to 96.1% with the relative standard deviations (RSDs) less than 10%. The detection limit of the method was 1.0 μg/L. The method is sensitive, simple, and suitable for the rapid determination of BPA in milk.

Key words: bisphenol A (BPA), high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), milk, monodisperse magnetic submicron particles, solid-phase extraction (SPE)