simultaneous determination of aflatoxin b1, bisphenol a, and 4-nonylphenol in peanut oils by liquid-liquid extraction combined with solid-phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry

An analytical method based on liquid-liquid extraction combined with solid-phase extraction and isotope dilution-ultra-high performance liquid chromatography-tandem mass spectrometry (uplc-ms/ms) was well developed for simultaneous determination of aflatoxin b1 (afb1), bisphenol a (bpa), and 4-nonylphenol (4-np) in peanut oil. after adding isotope internal standards, the samples were firstly diluted by normal hexane and then extracted by acetonitrile and carb/psa solid-phase extraction cartridge in sequence to obtain the extracted solution. all the extracted solution was merged and was subsequently dried to near dryness by a mild nitrogen stream. three target analytes were separated on a phenomenex luna c18 chromatographic column, quantified by an internal standard method and detected by esi positive (esi+) and negative (esi−) subsection acquisition modes under multi-reaction monitoring (mrm) conditions. results demonstrated that the three target analytes exhibited excellent linearity in their corresponding concentration ranges of 0.1–100.0 μg/l with correlation coefficients all greater than 0.998. the corresponding method limits of quantitation (mloq, s/n = 10) of afb1, bpa, and 4-np were 0.2, 1.0, and 2.0 μg/kg, respectively. moreover, the mean recoveries for negative samples spiked at three concentration levels were calculated between 87.7 and 105.1% with relative standard deviation (rsd, n = 6) ranging from 2.2 to 7.9% and the interday precision (n = 5) ranging from 5.0 to 8.7%. finally, the method was successfully applied to analyze 52 peanut oil samples, and afb1 and 4-np were detected in 43 samples with the concentrations in the ranges of 0.5–69.4 and 9.3–77.8 μg/kg, respectively. none of bpa was detected in any samples.