PFAS Isomers
PFHxS 19F -NMR spectrum
PFNA 1 9F -NMR spectrum
During the last few years, the difference between isomeric forms of PFAS substances has emerged as an additional factor which affects the physicochemical properties of the compounds. This can have an effect in the adsorption on solid phases, the distribution in different environmental compartments etc. Some researchers suggest that linear PFAS are more readily adsorbed to soil and sediments, whereas branched isomers are more likely to remain in water compartments probably due to the differences in polarity between the two isomers. Studies in humans and animals have shown that the linear PFOS isomer is more likely to accumulate in animals whereas in humans, the branched isomer is more likely to accumulate. Above two 19F -NMR spectrums are shown. The one (PFNA) showing only linear chain with signal for the CF3 group at -80 ppm and the CF2 groups in the range of -115 to -125 ppm. On the other hand, the spectrum for PFHxS shows additional signals e.g. at -71 ppm indicating the presence of branched isomers in the product next to the signals for the linear chain.
5
Made with FlippingBook. PDF to flipbook with ease