Interlaboratory Study of Polyethylene and Polydimethylsiloxane Polymeric Samplers for Ex Situ Measurement of Freely-Dissolved Hydrophobic Organic Compounds in Sediment Porewater
Citation of Original Publication
Lotufo, G.R., Michalsen, M.M., Reible, D.D., Gschwend, P.M., Ghosh, U., Kennedy, A.J., Kerns, K.M., Rakowska, M.I., Odetayo, A., MacFarlane, J.K., Yan, S. and Bokare, M. (2022), Interlaboratory Study of Polyethylene and Polydimethylsiloxane Polymeric Samplers for Ex Situ Measurement of Freely-Dissolved Hydrophobic Organic Compounds in Sediment Porewater. Environ Toxicol Chem. Accepted Author Manuscript. https://doi.org/10.1002/etc.5356
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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This study evaluated the precision and accuracy of multi-laboratory measurements for determining freely dissolved concentrations (C free) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in sediment porewater (PW) using polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) polymeric samplers. Four laboratories exposed performance reference compound (PRC) pre-loaded polymers to actively mixed and static ex situ sediment for ~ 1 month; two laboratories had longer exposures (i.e., 2 and 3 months). For C free results, intra-laboratory precision was high for single compounds (CV ≤50%), and for most PAHs and PCBs interlaboratory variability was low (magnitude of difference ≤ factor 2) across polymers and exposure methods. Variability was higher for the most hydrophobic PAHs and PCBs, which were present at low concentrations and required larger PRC-based corrections, and for naphthalene, likely due to differential volatilization losses between laboratories. Overall, intra- and interlaboratory variability between methods (PDMS vs. LDPE, actively mixed vs. static exposures) was low. Results showed C free polymer equilibrium was achieved in ~ 1 month during active exposures, suggesting use of PRCs may be avoided for ex situ analysis using comparable active exposure; although such ex situ testing may not reflect field conditions. Polymer-derived C free concentrations for most PCBs and PAHs were on average within a factor of 2 compared to concentrations in isolated PW, which were directly measured by one laboratory; difference factors of up to 6 were observed for naphthalene and the most hydrophobic PAHs and PCBs. C free results were similar for academic and private sector laboratories. Demonstrated accuracy and precision for determination of C free using polymer sampling is anticipated to increase regulatory acceptance and confidence in method use.