Optimization of extraction methods for the analysis of PFOA and PFOS in the salty matrices during the wastewater treatment

Water bodies of numerous countries and regions in the world have been contaminated to various extents with the widespread production and usage of perfluoroalkyl substances (PFASs). Both domestic and industrial wastewaters become one of the important sources for the PFAS contaminations in natural water bodies, due to the incomplete treatment. Usually, the artificial wastewaters are complex and have high concentrations of inorganic salts, which could result in the matrix effects during the process of analysis for PFASs, contributing to quantify the target compounds inaccurately. In order to monitor the concentrations of PFAS contaminants precisely, suitable extraction methods were compared focusing on the matrix effects and characters of green analytical chemistry during the detection of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) existing with several common inorganic salts in wastewaters. The results showed that the analytical values of PFOA and PFOS were 2.8-3.6 times and 3.0-5.2 times higher than the theoretical values, respectively. The liquid-liquid extraction (LLE) and solid phase extraction (SPE) methods were used to reduce the matrix effects originated from inorganic salts, consequently the SPE method was confirmed as the optimal extraction method, based upon both the recoveries and green procedures. Combined with the application of the best parameters in real industrial wastewaters, indicating the present study would provide an accurate and green quantitative analysis of PFASs in salty wastewaters.