Direct measurements of polyurethane foam (PUF) ‒ air partitioning coefficients for chemicals of emerging concern capable of equilibrating in PUF disk samplers.

Organophosphate esters (OPEs), novel flame retardants (NFRs) and organochlorine pesticides (OCPs) are volatile to semi-volatile chemicals and therefore susceptible to approach equilibrium during typical deployments of polyurethane foam (PUF) disk passive air samplers. A generator column approach was used to measure the PUF-air partitioning coefficient (K) for these targeted chemicals. K values are required for these chemicals to estimate sampled equivalent air volumes, which vary substantially with temperature. Log K measurements were made at temperatures ranging from +6 to +35 °C and resulting values ranged from 5.14 to 7.77. Enthalpies of phase change for PUF to air (ΔH, kJ/mol) ranged from 51.3 to 98.9. Two relationships of log K versus log K (K) were derived, grouping OPEs and NFRs separately. The relationship for NFRs was in fair agreement (within about 0.6 log units) to a long-standing relationship by Shoeib and Harner (since 2002) for polychlorinated biphenyls (PCBs). However, the estimated values using Shoeib-Harner relationship substantially underestimates K for the OPEs than directly measured values (by about an order of magnitude). These findings highlight the importance of the direct measurements of K for emerging classes of chemicals whose concentrations are at risk of equilibrating in PUF disk samplers.