Field Evaluation of the Sentinel™ Integrative Passive Sampler for the Measurement of Perfluoroalkyl and Polyfluoroalkyl Substances in Water Using a Modified Organosilica Adsorbent

A passive sampler specifically designed to measure perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water was tested in four study areas (Ellsworth and Peterson Air Force bases, CO and SD; the Ohio River, OH, WV, KY, IN; and the Santa Ana River, CA). Locations included both groundwater and surface water locations. Over the 2-year study, 96 passive samplers were deployed at 33 sample locations and were compared with co-collected grab samples, all of which were measured for 19 PFAS analytes by HPLC–MS/MS. Correlations were observed (typically within 2× difference) between aqueous PFAS concentrations measured by passive versus discrete grab samples across over 5 orders of magnitude in concentration (0.5 to 150,000 ng/L). Overall relative percent difference between grab and passive results displayed a median of 18% (interquartile range of −19 to 73%). Detection limits were around 1 ng/L for a 2-week sampling time with sampling rates ranging from 12 to 70 mL/day in flowing systems. Duplicate samplers were deployed in all study areas which indicated a 14 to 42% (median 24%) relative standard deviation in the precision of passive sampling. Larger variances were seen with sites with higher and potentially more variable water flows. A sub-set of duplicate samplers were measured by a commercial laboratory which returned equivalent data to research laboratory measurements (43 [±26 SD]% relative percent difference). Standardized protocols and calculation methods were developed to facilitate expanded testing and future broader use of passive sampling for PFAS by site investigators.