Polymers as Reference Partitioning Phase: Polymer Calibration for an Analytically Operational Approach To Quantify Multimedia Phase Partitioning

Abstract

Polymers are increasingly applied for the enrichment of hydrophobic organic chemicals (HOCs) from various types of samples and media in many analytical partitioning-based measuring techniques. We propose using polymers as a reference partitioning phase and introduce polymer-polymer partitioning as the basis for a deeper insight into partitioning differences of HOCs between polymers, calibrating analytical methods, and consistency checking of existing and calculation of new partition coefficients. Polymer-polymer partition coefficients were determined for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) by equilibrating 13 silicones, including polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) in methanol-water solutions. Methanol as cosolvent ensured that all polymers reached equilibrium while its effect on the polymers' properties did not significantly affect silicone-silicone partition coefficients. However, we noticed minor cosolvent effects on determined polymer-polymer partition coefficients. Polymer-polymer partition coefficients near unity confirmed identical absorption capacities of several PDMS materials, whereas larger deviations from unity were indicated within the group of silicones and between silicones and LDPE. Uncertainty in polymer volume due to imprecise coating thickness or the presence of fillers was identified as the source of error for partition coefficients. New polymer-based (LDPE-lipid, PDMS-air) and multimedia partition coefficients (lipid-water, air-water) were calculated by applying the new concept of a polymer as reference partitioning phase and by using polymer-polymer partition coefficients as conversion factors. The present study encourages the use of polymer-polymer partition coefficients, recognizing that polymers can serve as a linking third phase for a quantitative understanding of equilibrium partitioning of HOCs between any two phases.

Detection of tris(2,3-dibromopropyl) phosphate and other organophosphorous compounds in Arctic rivers

“…In general, these silicone rubber-water partition coefficients are not very high but in agreement with reported/calculated logK p values of 3.71 ‡ . In general, lower logK pw have been reported for SSP silicone rubber than for AlteSil™ (Gilbert et al 2016). This is also the case for TDBrPP.…”

Transferring mixtures of chemicals from sediment to a bioassay using silicone-based passive sampling and dosing

“…Loading methods based on solvent evaporation have previously been used for passive dosing with halogenated and non-halogenated aromatic chemicals. 42,43 Also, recently Gilbert et al 44 loaded silicone polymers with PCBs using isooctane, which was thereaer allowed to evaporate. To conrm that all loading solvent had evaporated, the weight of dosing vials (n ¼ 9) containing 0.03 g of polymer was determined before loading and aer evaporation of the solvent.…”

“…Hence, partition coefficients are polymer-specic as the content of different additives and llers (e.g. diatomaceous earth 44 ) may vary between suppliers and thus cause differences in partitioning properties. In an extensive review by DiFilippo et al, 56 it was concluded that improper measuring techniques were a main source of error for the K p-w and as opposed to Smedes et al, no signicant effect associated with the supplier of the polymers was found.…”

Comparing polyethylene and polyoxymethylene passive samplers for measuring sediment porewater concentrations of polychlorinated biphenyls: Mutual validation and possible correction by polymer-polymer partition experiment

“…The accuracy of Kpw might explain a large fraction of the uncertainty in PSMs (Lydy et al, 2014) because accurate determination of high Kpw values for HOCs is challenging. Recently, Gilbert et al (2016) proposed to measure and use polymer-polymer partition coefficients for calibration, property evaluation, and data consistency tests of multiple passive samplers. This is a promising approach for the consistency test of sediment passive samplers because polymer-polymer partition coefficients can be much more accurately measured than polymer-water partition coefficients (Gilbert et al, 2016), primarily due to the fact that the error-prone measurement of low aqueous phase concentrations can be avoided.…”