An LC-MS/MS method for the quantitative determination of 57 per- and polyfluoroalkyl substances at ng/kg levels in different food matrices

To enable the monitoring of a wide scope of per- and polyfluoroalkyl substances (PFAS) in the ng/kg level in foodstuffs, an LC-MS/MS method comprising 57 analytes was developed and validated in seven different matrices (milk powder, milk-based infant formula, meat-based baby food puree, fish and fish oil, fresh egg, and soluble coffee). The analytical approach was based on an acetonitrile:water extraction followed by solid phase extraction clean-up with subsequent quantification of the extracted analytes either by isotope dilution (55 compounds) or by standard addition (2 compounds) mass spectrometry. The validation criteria followed the guidance document for the analysis of PFAS issued by the European Union Reference Laboratory for Halogenated Persistent Organic Pollutants. The lowest limits of quantification (LOQs) for the four recently regulated compounds (L-PFOS, PFOA, PFNA, L-PFHxS) were set at 0.010 µg/kg in baby and infant foods (as sold) but also in dairy ingredients. Exception was for PFOA in milk powder due to too large variability in the repeatability. Applicability of the method was further demonstrated in 37 commodity check matrices. Overall validation data demonstrated the robustness of the method for most of the compounds and the LOQs achieved were low enough to ensure compliance with Commission Regulation EU 2022/2388 but also to support future collection of occurrence data in ng/kg level in food.

为实现对食品中ng/kg级别的全氟和多氟烷基物质（per- and polyfluoroalkyl substances, PFAS）的广谱监测，本研究开发了一种包含57种分析物的液相色谱-串联质谱（Liquid Chromatography-Tandem Mass Spectrometry, LC-MS/MS）方法，并在7种不同食品基质（奶粉、乳基婴儿配方食品、肉基婴儿辅食泥、鱼类及鱼油、鲜鸡蛋、速溶咖啡）中完成了方法验证。该分析方法采用乙腈-水萃取结合固相萃取净化的前处理流程，随后通过质谱分别采用同位素稀释法（针对55种化合物）或标准加入法（针对2种化合物）对萃取得到的分析物进行定量。方法验证准则遵循欧盟卤化持久性有机污染物参考实验室发布的全氟和多氟烷基物质分析指导文件。四种最新纳入监管的化合物（L-PFOS、PFOA、PFNA、L-PFHxS）在市售婴儿辅食、婴幼儿食品及乳类原料中的最低定量限（Limit of Quantitation, LOQs）设定为0.010 µg/kg。但奶粉基质中的PFOA除外，原因是其重复性变异度过大。该方法的适用性还在37种商品质控基质中得到了验证。整体验证数据表明，该方法对绝大多数分析物均具有良好的稳健性，且达成的定量限足够低，既可满足欧盟委员会法规（EU）2022/2388的合规要求，也可为未来收集食品中ng/kg级别的PFAS检出数据提供支撑。