凝胶渗透色谱法净化-同位素稀释-超高效液相色谱-串联质谱法测定奶粉中4-壬基酚

Determination of 4-nonylphenol in milk powder by gel permeation chromatography purification and isotopic dilution-ultra performance liquid chromatography-tandem mass spectrometry

目的建立凝胶渗透色谱法(gel permeation chromatography, GPC)净化技术结合同位素稀释的超高效液相色谱-串联质谱法测定奶粉中的4-壬基酚的检测方法。方法样品以乙酸乙酯和环己烷超声提取后,上清液用GPC进行净化,然后进行旋转蒸发浓缩。在优化的仪器条件下,采用电喷雾离子源负离子模式采集离子对,多反应监测模式扫描测定,同时结果使用d4同位素内标校正。结果 4-壬基酚在1.0~100μg/L范围内呈较好线性,相关系数r2为0.9998,在2.0、10.0、20.0μg/kg 3个浓度添加水平下的平均回收率为87.3%~96.6%,相对标准偏差为1.58%~3.35%。方法检出限和定量限分别为0.6和2.0μg/kg。结论该方法操作简单高效,有效校正结果偏差,回收率高、灵敏度高、重复性好,可有效测定奶粉中4-壬基酚含量。

Objective To establish a method for determination of 4-nonylphenol in milk powder by gel permeation chromatography(GPC) purification technology combined with isotope dilution method-ultra performance liquid chromatography-tandem mass spectrometry. Methods Samples were ultrasonic extracted with ethyl acetate and cyclohexane, then the supernatant was purified by GPC and finally concentrated by rotary evaporation. Under the optimized instrument conditions, ion pairs were acquisited with electrospray negative mode ionization and detected with multiple reaction monitoring mode and the results were regulated by d4 isotope internal standard. Results The internal standard calibration curves of 4-nonylphenol exhibited good linearity within the concentrations of 1.0-100 μg/L with the correlation coefficient r2 0.9998. The average recovery rates of the 3 concentration levels(2.0、10.0、20.0 μg/kg) were 87.3%-96.6%, while the relative standard deviations were 1.58%-3.35%. The limits of detection and limits of quantitation were 0.6 and 2.0 μg/kg. Conclusion This method is simple and efficient in operation, effective in correcting result deviation, high recovery rate, high sensitivity and good repeatability, and can effectively determine the content of 4-nonylphenol in milk powder.