Automated method for determination of dissolved organic carbon–water distribution constants of structurally diverse pollutants using pre‐equilibrium solid‐phase microextraction

Abstract

Dissolved organic carbon (DOC) plays a key role in determining the environmental fate of semivolatile organic environmental contaminants. The goal of the present study was to develop a method using commercially available hardware to rapidly characterize the sorption properties of DOC in water samples. The resulting method uses negligible-depletion direct immersion solid-phase microextraction (SPME) and gas chromatography-mass spectrometry. Its performance was evaluated using Nordic reference fulvic acid and 40 priority environmental contaminants that cover a wide range of physicochemical properties. Two SPME fibers had to be used to cope with the span of properties, 1 coated with polydimethylsiloxane and 1 coated with polystyrene divinylbenzene polydimethylsiloxane, for nonpolar and semipolar contaminants, respectively. The measured DOC-water distribution constants showed reasonably good reproducibility (standard deviation ≤ 0.32) and good correlation (R(2) = 0.80) with log octanol-water partition coefficients for nonpolar persistent organic pollutants. The sample pretreatment is limited to filtration, and the method is easy to adjust to different DOC concentrations. These experiments also utilized the latest SPME automation that largely decreases total cycle time (to 20 min or shorter) and increases sample throughput, which is advantageous in cases when many samples of DOC must be characterized or when the determinations must be performed quickly, for example, to avoid precipitation, aggregation, and other changes of DOC structure and properties. The data generated by this method are valuable as a basis for transport and fate modeling studies.

Dissolved Organic Carbon Quality and Sorption of Organic Pollutants in the Baltic Sea in Light of Future Climate Change

“…Error values based on the reproducibility of the method are presented elsewhere. 33 There were significant spatial differences in the K DOC values. These are presented in Figure 4 and will be discussed in the order from north to south.…”

“…SPME was performed in the kinetic (nonequilibrium) mode. A detailed description of both log K DOC analytical methods and calculations can be found elsewhere . A brief description follows below.…”

Sorption of Highly Hydrophobic Organic Chemicals to Organic Matter Relevant for Fish Bioconcentration Studies

“…Only freely dissolved substances are bioavailable, but significant amounts of the test substance which are bound by sorption processes are extracted as well from the aqueous phase. ,− While the determination of freely dissolved analyte concentrations was challenging and laborious for a long time, the use of nonexhaustive solid-phase microextraction (SPME) is straightforward. − It allows discrimination between bound and freely dissolved test substances, with the freely dissolved analyte concentrations corresponding to the bioavailable concentrations for organisms. − In addition to physiological explanations, the impact of sorption processes on the bioavailability of test substances has been discussed as a major reason for the phenomenon of the “hydrophobicity cutoff”. This means that the correlation between measured BCF values and n -octanol–water partition coefficients ( K OW ) of HOCs levels off or even declines above log K OW 5–6, which indicates that those substances bioconcentrate less than expected on the basis of their hydrophobicity. ,, The influence of OM on the sorption of several (highly) HOCs (log K OW > 5–6) was studied with a broad range of different qualities and origins of suspended and dissolved organic matter (DOM). ,− Laboratory BCF systems are less complex compared to environmental systems. Nevertheless, a systematic examination of the interaction of (highly) hydrophobic test substances with natural OM occurring in flow-through fish test systems is missing.…”

Atmospheric pathways of chlorinated pesticides and natural bromoanisoles in the northern Baltic Sea and its catchment

“…Results are displayed in Fig. 3 for situations in which the pesticides are freely dissolved in water or partly bound to dissolved organic carbon (DOC) (Ripszam and Haglund 2015 ). Percentages of freely dissolved compounds ranged from >90 % for HCHs and ENSUL, 75–85 % for DIEL, ENDOs, and DAC, and 50–65 % for HCB and CHLs.…”