Determination of perfluorinated chemicals in food and drinking water using high-flow solid-phase extraction and ultra-high performance liquid chromatography/tandem mass spectrometry.

For this study, we developed methods of determining ten perfluorinated chemicals in drinking water, milk, fish, beef, and pig liver using high-flow automated solid-phase extraction (SPE) and ultra-high performance liquid chromatography/tandem mass spectrometry. The analytes were separated on a core-shell Kinetex C18 column. The mobile phase was composed of methanol and 10-mM N-methylmorpholine. Milk was digested with 0.5 N potassium hydroxide in Milli-Q water, and was extracted with an Atlantic HLB disk to perform automated SPE at a flow rate ranged from 70 to 86 mL/min. Drinking water was directly extracted by the SPE. Solid food samples were digested in alkaline methanol and their supernatants were diluted and also processed by SPE. The disks were washed with 40% methanol/60% water and then eluted with 0.1% ammonium hydroxide in methanol. Suppression of signal intensity of most analytes by matrixes was lower than 50%; it was generally lower in fish and drinking water but higher in liver. Most quantitative biases and relative standard deviations were lower than 15%. The limits of detection for most analytes were sub-nanograms per liter for drinking water and sub-nanograms per gram for solid food samples. This method greatly shortened the time and labor needed for digestion, SPE, and liquid chromatography. This method has been applied to analyze 14 types of food samples. Perfluorooctanoic acid was found to be the highest among the analytes (median at 3.2-64 ng/g wet weight), followed by perfluorodecanoic acid (0.7-25 ng/g) and perfluorododecanoic acid (0.6-15 ng/g).

Concentrations of perfluoroalkyl substances in foods and the dietary exposure among Taiwan general population and pregnant women.

This study quantified five perfluorocarboxylic acids (PFCAs) and two perfluorosulfonic acids in cereals, meats, seafood, eggs, pork liver, and milk in Taiwan using ultra-performance liquid chromatography-tandem mass spectrometry and evaluated the dietary exposure of the general population and pregnant women using per capita consumption and a questionnaire, respectively. Perfluorooctanoic acid (PFOA) and PFCAs of 10-12 carbons were found in almost all of the samples in considerable concentrations in rice and pork liver, reaching as high as 283 ng/g (PFOA in pork liver); the levels are two to three orders of magnitude higher than previous reports. Perfluorooctane sulfonate (PFOS), the most frequently mentioned perfluoroalkyl substance, was rarely detected in many food items (detection frequencies <20% in rice, flour, pork, chicken, salmon, squid, eggs, and milk) at <0.4 ng/g, except for beef, pork liver and some seafood (detection frequencies: 100%, GMs: 0.05-3.52 ng/g). Compared to populations in Western countries, people in Taiwan are exposed to much more perfluorohexanoic acid, PFOA, perfluorodecanoic acid, and perfluoroundecanoic acid (11.2, 85.1, 44.2, and 4.45 ng/kg b.w./day, respectively), mainly due to the higher contaminations in food. The exposure of 8.0 µg PFOA/person/day in the 95 percentile of pregnant women was due to their frequent consumption of pork liver.