Investigation Of Residual Levels And Residue Analysis On Perfluoroalkyl Substances In Milk

Perfluorinated alkylated substances(PFASs) are one emerging class of organic compounds which are featured by representative structural characteristics with long alkyl chain, while hydrogen have all been replaced by fluorine and the functional group in the end such as carboxyl(–COOH) and sulfonate(-SO3H) groups. Since the discovery of these compounds, they were widely used in a variety of areas. The high stability of carbon-fluoride bonds results in extreme difficulty of the PFASs to biodegrade over time in the environment. Currently, the traces of PFASs were found in soil, drinking water, food, human serum and other matrixes. An important pathway of human intaking PFASs is via diet. This study established a method of simultaneous determination of 20 kinds of PFASs, investigated the contamination levels of PFASs in milk and evaluated health risks of residents exposed to PFASs via drinking milk. The main results as follows:(1) This research developed a Qu ECh ERs combining with on-Line interference trapping LC-MS/MS method for determination of 20 PFASs in milk. The samples were extracted and cleaned up following the Qu ECh ERS procedure and then subject to an online interference trapping LC-MS/MS analysis with Zorbax EP-C18(4.6×50 mm,5 μm) column and separation with Poroshell 120 EC-C18 column(2.1×100 mm, 2.7 μm). With quantitation using stable isotope labeled internal standards, 20 PFASs showed excellent linear dynamic ranges, with regression coefficients of 0.997 or above. The LODs and LOQs for perfluorinated carboxylic acids(PFCAs) were 0.0030 μg/L and 0.010 μg/L, respectively; and those for perfluorinated sulfonic acids(PFSAs) were 0.010 μg/L and 0.050 μg/L, respectively. At the three spiking levels including LOQs, the average recoveries for PFCAs ranged from 78.50% to 111.1% with the RSD(n=6) within 1.230-13.05%; and those for PFSAs were within 72.80-104.9% with the RSD(n=6)ranged from 3.530-14.77%. The developed method was sensitive, rapid, and accurate, and was successfully applied for real sample screening.(2) By detecting the concentration of PFASs in 660 milk samples collected at 31 provinces and municipalities in China. The results indicated that the contamination levels of milk in our city were serious. There were 16 PFASs were detected and the detection rates of four PFASs including PFHx DA, PFHx A, PFOA and PFOS were more than 40%. The highest contamination level came from PFOA and PFOS with the average concentrations of 0.093 μg/L and 0.126 μg/L.The detected number of compounds of PFCAs was significantly higher than that of PFSAs. And the discovery of PFSAs in milk is more frequent. Among the contamination situation of PFASs in milk from 31 provinces and municipalities of China, the higher pollution level were found in coastal cities and fluorine chemical industry developed cities. More than 10 kinds of PFASs were detected from Guangdong, Liaoning, Hebei, Shanghai and they have the most kinds of PFASs.While in the northwest cities like Guangxi, Tibet, Qinghai, PFASs were found the less kinds and concentration of PFASs in milk of these regions were similarity.(3) Based on contamination levels of PFASs in milk from China, using the daily Rf D provided by European Food Safety Authority, this study evaluated the health risk of residents expose to PFASs via milk. The results of the survey show that the HR from PFASs in milk which was produced at 31 provinces and municipalities in China was far less than 1and the HR from PFOS was higher than PFOA. The potential hazards from PFOA and PFOS were not found to human in recent research.