Bioconcentration of Organic Chemicals:  Is a Solid-Phase Microextraction Fiber a Good Surrogate for Biota?

Abstract

When organic chemicals are extracted from a water sample with solid-phase microextraction (SPME) fibers, the resulting concentrations in exposed fibers are proportional to the hydrophobicity of the compounds. This fiber accumulation is analogous to the bioconcentration of chemicals observed in aquatic organisms. The objective of this study was to investigate the prospect of measuring the total concentration in SPME fibers to estimate the total body residue in biota for the purpose of risk assessment. Using larvae of the midge, Chironomus riparius and disposable 15-microm poly(dimethylsiloxane) fibers, we studied the accumulation and accumulation kinetics of a number of narcotic compounds with a range of log K(ow) between 3 and 6. The fibers, which have a larger surface area-to-volume ratio, had consistently higher uptake and elimination rate constants (k1 and k2, respectively) than midge larvae and accumulated the chemicals 5 times faster. Comparison of the relationships of the partition coefficients K(PDMS-water) and K(midge-water) (lipid-normalized) to log K(ow) for all compounds yielded a factor of 28 for translating fiber concentrations to biota concentrations. This factor can be used to estimate internal concentrations in biota for compounds structurally similar to the compounds in this study. The exact chemical domain to which this factor can be applied needs to be defined in future research.

Bioavailability of organochlorine compounds in aqueous suspensions of fullerene: Evaluated with medaka (Oryzias latipes) and negligible depletion solid-phase microextraction

“…All experimental data of the uptake profiles to nd-SPME fiber were fitted to a first-order one-compartment uptake model modified from reference (Sijm and Vanderlinde, 1995;Leslie et al, 2002) using Graphpad Prism (V 4.1, GraphPad Software, San Diego, CA, USA), the details were described in data analysis section (Supplementary material). Mean values were calculated from the three replicates and the standard deviations were presented.…”

Chemical techniques for assessing bioavailability of sediment-associated contaminants: SPME versus Tenax extraction

“…21,28,35,36 In this case, exposure duration is particularly important because equilibrium of the contaminant may not have been reached between the matrix and either the fiber or organism because the rates at which the contaminant absorbs to the fiber and is taken up by the organism are likely to be quite different. 37 If the equilibrium condition is not fulfilled, the SPME fibers concurrently exposed with the organisms should not be considered as a passive sampler, but rather an operational nonexhaustive extraction technique for bioavailability estimation. 21 Conversely, other studies have compared C f to chemical residues in organisms at the completion of exposure when the fiber and the organism have reached equilibrium and steady state, respectively.…”

Peer Reviewed: Internal Exposure: Linking Bioavailability to Effects

“…A direct comparison of measured internal concentrations in organisms versus some threshold values-the socalled critical internal concentrations-is a promising alternative to evaluations based on external concentrations in water, soil, or sediment. New developments in sampling techniques fit well into such an internal-concentration-based assessment (44,45).…”