John Wiley & Sons, Ltd.

Review of polyoxymethylene (POM) passive sampling methods for quantifying freely‐dissolved pore water concentrations of hydrophobic organic contaminants

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Methods involving polyoxymethylene (POM) as a passive sampler are increasing in popularity to assess contaminant freely‐dissolved porewater concentrations in soils and sediments. These methods require contaminant‐specific POM‐water partition coefficients, KPOM. Specific methods for determining KPOM perform reproducibly (within 0.2 log units). However, different methods can lead to highly varying KPOM values (up to two log units), especially for polycyclic aromatic hydrocarbons (PAHs). To account for this, the authors tested the influence of key methodological components in KPOM determinations, including POM thickness, extraction procedures, environmental temperature and salinity, as well as uptake kinetics in mixed and static systems. All inconsistencies in the peer‐reviewed literature can be accounted for by thick POM materials (500 μm or thicker) not achieving equilibrium (causing negative biases up to one log unit), or by POM extraction procedures not ensuring quantitative extraction (causing negative biases up to two log units). Temperature can also influence KPOM, though all previous literature studies were carried out at room temperature. This study found KPOM values at room temperature are independent (within 0.2 log units) of POM manufacture method, thickness between 17 to 80 μm, and salinity between 0 to 10 %. Regarding kinetics, monochoro to hexachloro ‐polychlorinated biphenyls (PCBs) were within 0.2 log units of equilibrium after 28 days in the mixed system, but only dichloro‐PCBs achieved near equilibrium after 126 days in the static system. Based on these insights recommended methods and KPOM values to facilitate inter‐laboratory reproducibility are presented. This article is protected by copyright. All rights reserved

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