Perfluoroalkyl acids (PFAAs) with isomer analysis in the commercial PFOS and PFOA products in China

Abstract

Perfluoroalkyl acids (PFAAs) have been widely used in consumer and industrial products for decades and are widely detected in the environment and humans all over the world. The information on the isomeric profiles of commercial products is important to identify the manufacturing origins of PFAAs in the environment. For the first time, the PFAA compositions and isomeric profiles of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) were reported in three PFOS and five PFOA commercial products manufactured in China. The purity of the three PFOS products was 76.7–80.6%. The major impurity in the PFOS products is PFOA, which contributes more than 10%. Other impurities include perfluorohexanesulfonate (PFHxS), perfluorohexanoate (PFHxA) and perfluoroheptanoate acids (PFHpA). The percentage of linear PFOS (n-PFOS) in the three products was 66.2–71.9%, similar to that in the product manufactured by 3M (70.3%). The purity of the five PFOA products was relatively high (94.0–95.8%), and the major impurity was PFOS (2.06–3.09%). The percentage of n-PFOA in the five PFOA products was 76.4–77.9%, which was similar to that in the 3M PFOA (78%). Although it is widely accepted that telomerization is currently the predominant manufacturing method for PFOA, yielding an isomerically pure and linear product, the results in the present study suggest that electrochemical fluorination is still used by some manufacturers in China.