title: [Analysis of perfluoroalkyl substances and their precursors in eighteen market milk].
abstract: OBJECTIVE
  To explore the level of perfluoroalkyl substances (PFASs) and their precursors in 18 market milk samples of China.
  
  
  METHODS
  The 18 milk samples were selected in 8 provinces of China, including Ningxia, Neimeng, Beijing, Tianjin, Hebei, Shanxi, Chongqing, and Guangdong. 8 PFASs and 11 PFAS precursors were measured by ultra-high performance liquid chromatography-tandem quadruple mass spectrometry (UPLC-MS/MS). The dietary exposure assessment was made.
  
  
  RESULTS
  Three PFASs were detected in milk samples which were PFOA, PFUdA, and PFOS. The numbers of detected samples were 5, 12, and 14, respectively. Their concentration ranges were < Limit of determination (LOD)-431.94 pg/ml, < LOD -15.95 pg/ml and < LOD -126.98 pg/ml, respectively. Three PFAS precursors were also found above the detection limits, namely, 4:2 FTS, 6:2 FTS, and 6:2 diPAP. Only one sample was detected 4:2 FTS at the concentration of 3.75 pg/ml. The detected samples of 6:2 FTS and 6:2 diPAP were 12 and 3. Their concentration ranges were < LOD -2.49 pg/ml and < LOD -24.56 pg/ml, respectively. The ranges estimated daily intake of PFOA and PFOS of the detected samples were 2.49 × 10⁻³-405.89 × 10⁻³ ng · kg⁻¹ · d⁻¹ and 36.10 × 10⁻³-119.32 × 10⁻³ ng · kg⁻¹ · d⁻¹.
  
  
  CONCLUSIONS
  Our results suggested that there were different contamination levels of PFASs and their precursors in the 18 market milk produced from different regions in china. The estimated daily intake of PFASs from the milk in our study were far below the tolerable daily intake set by European Union (PFOS: 150 ng · kg⁻¹ · d⁻¹, PFOA: 1 500 ng · kg⁻¹ · d⁻¹).
authors: Department of Chemistry, China National Center for Food Safety Risk Assessment and Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China.
authors: Lin
authors: L
authors: Yang
authors: Meng
authors: M
authors: Wang
authors: Email: lijg@cfsa.net.cn.
authors: Jingguang
authors: J
authors: Li
authors: Yuxin
authors: Y
authors: Wang
authors: Yunfeng
authors: Y
authors: Zhao
authors: Yongning
authors: Y
authors: Wu
mesh_terms: D000818:Animals; D002681:China; D002853:Chromatography, Liquid; D003611:Dairy Products; D005466:Fluorocarbons; D005506:Food Contamination; D006801:Humans; D013058:Mass Spectrometry; D008892:Milk; D053719:Tandem Mass Spectrometry
chemical_list: D005466:Fluorocarbons