Lab Matters Spring 2023 | Page 13


Meeting the Challenge for Measuring Trace Levels of PFAS in Water

By Jenifer Lewis , senior market development manager , Environmental Markets , Waters
Per- and polyfluorinated alkyl substances ( PFAS ) are currently one of the most discussed and researched environmental contaminants . Labeled as “ forever chemicals ,” they are manufactured organic compounds that have been used in a variety of common consumer products , like non-stick cookware , food packaging , stain resistant carpets , waterproof fabrics and very effective firefighting foams . Their widespread use has resulted in deposition into the environment , where they have eventually found their way into public drinking water and food supplies .
Studies of water supplies in the United States have confirmed that PFAS are present in drinking water across the nation and are present in the blood of people and animals all over the world . Current research has linked exposure to PFAS to a range of health effects including an increased risk of certain cancers ( prostate , kidney and testicular ), suppression of the body ’ s immune system and reduced vaccine response , and reproductive and developmental effects .
In 2022 , the US Environmental Protection Agency ( US EPA ) updated their PFAS Health Advisory Limits ( HALs ) in response to new toxicity research studies . US EPA describes health advisory limits as “ concentrations of such drinking water contaminants at which adverse health effects are not anticipated to occur over specific exposure durations , such as one-day , 10-days or a lifetime .” The more toxic chemicals of perflurooctanic acid ( PFOA ) and perflourooctane sulfonic acid ( PFOS ) have limits set at ultra-low values of 0.004 and 0.02 parts per trillion ( ppt ) respectively . Considering that 1 ppt is equivalent to 1 drop of water spread out in 20 Olympic size swimming pools , measuring these trace level concentrations can present an analytical challenge .
Liquid chromatography coupled to tandem mass spectrometry ( LC – MS / MS ), is the ideal analytical solution for delivering high sensitivity and analyte
Waters ACQUITY™ Premier UPLC™ coupled to Xevo™ TQ-Absolute . Photo : Waters
specificity for PFAS . The Waters Xevo™ TQ-Absolute utilizes a new detector technology designed specifically to enhanced sensitivity for challenging negative ionizing compounds , like PFAS . The ACQUITY PREMIER liquid chromatograph incorporates MaxPeak™ surface technology , which provides pre-conditioned fluid paths to reduce analyte to metal interactions , and improve sensitivity and reproducibility .
Sample enrichment using solid phase extraction ( SPE ) is another tool that can be utilized to enhance the sensitivity of water testing methods like US EPA 537.1 and 533 prior to sample injection . Typically , a 250-fold concentration is achieved by loading a 250 ml sample aliquot onto an extraction cartridge , eluting compounds of interest with solvent , and concentrating to 1 ml or less just prior to analysis .
Background PFAS contamination from routine materials in laboratories must be controlled to meet sub-ppt limits of detection . PFAS are frequently found at trace levels as impurities in commonly used laboratory items , like polytetrafluoroethylene products ( PTFE ), solvent lines , aluminum foil , sharpies and methanol .
The combination of the enhanced sensitivity of the Xevo™ TQ Absolute , with SPE sample enrichment techniques , can provide a path for meeting the demand for detection of PFAS at increasingly lower concentrations . LC-MS / MS is an uncomplicated platform that is easy to operate and designed for demanding , trace level , quantitative applications .
To learn more about comprehensive analytical workflow solutions please visit Waters . com / PFAS . To learn more about PFAS reference materials and proficiency testing support please visit ERAQC . com / PFAS . g
Waters is an APHL Platinum Level Sustaining Member .
Spring 2023 LAB MATTERS 11