Halomethanesulfonic acids - a new class of polar disinfection by-products: standard synthesis, occurrence, and indirect assessment of mitigation options.

Halomethanesulfonic acids (HMSAs) are recently discovered polar disinfection byproducts without commercially available reference materials. To allow for their accurate quantification, we successfully synthesized standards for the four presumably most prevalent HMSA congeners: chloromethanesulfonic acid, bromomethanesulfonic acid, dichloromethanesulfonic acid, and bromochloromethanesulfonic acid. After structure confirmation and quantification with high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy, we integrated them into a multilayer solid phase extraction and hydrophilic interaction liquid chromatography-tandem mass spectrometry method dedicated to the analysis of polar water contaminants. With this method we monitored HMSAs in drinking water production plants from four European countries and tap water samples taken in six countries. HMSAs were detected in the low mu g/L range after the chlorination step during drinking water production, all tap waters samples, and two surface waters used for drinking water production. Concentrations in tap water samples ranged from 0.07 mu g/L to 11.5 mu g/L while the HMSA concentrations in surface waters were in the range of 100 ng/L. We utilized the HMSA formation potential to indirectly assess the behavior of hitherto unknown HMSA precursors, consequently identifying ozonation, filtration through activated carbon, and reverse osmosis as efficient removal tools for HMSA precursors, thus limiting their formation during subsequent water disinfection.