Analysis of perfluorinated compounds in sludge liquid extraction and high performance liquid chromatography-tandem mass spectrometry

Abstract

Perfluorinated compounds are emerging persistent organic pollutants. Wastewater treatment plants are reported to be one of their primary sources. However; a standard analytical method for sludge samples has not been set up. A novel and rapid analytical method based on the liquid extraction; followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was set up for 7 perfluorocarboxylic acids (PFCAs) and their precursors, 6: 2 and 8: 2 unsaturated flourotelomer carboxylic acids (FTUCAs), and 2 perfluoroalkyl sulfonates vPFASs) and their precursors; 5 derivates of sulfonamide in sludge. The parameters of methanol extraction, including pH, sonication temperature and time, and eluent volume were optimized. The extraction method was optimized as neutral extraction under sonication at 40 °C for 10 min, and it was successfully used for the analysis of perfluorinated compounds in the sludge samples. The linear calibration curves were obtained in the ranges of 0. 1 - 20 μg/L for PFCAs and 6:2/8:2 FTUCA and 0. 25 - 50 μg/L for PFASs and their precusors with linear correlation coefficients larger than 0. 99. The recoveries of the target compounds ranged from 74% to 141% (except for FTUCAs) and the limits of quantification ranged from 0. 6 to 30 μg/kg (dry weight). The use of internal standards can well correct the ion suppression (or enhancement) induced by co-eluting components present in the sample extracts, and improve the quantitative accuracy.