Assessing bioavailability of DDT and metabolites in marine sediments using solid‐phase microextraction with performance reference compounds

Abstract

Solid-phase microextraction (SPME) has often been used to estimate the freely dissolved concentration (Cfree) of organic contaminants in sediments. A significant limitation in the application of SPME for Cfree measurement is the requirement for attaining equilibrium partition, which is often difficult for strongly hydrophobic compounds such as DDT. A method was developed using SPME with stable isotope-labeled analogues as performance reference compounds (PRCs) to measure Cfree of DDT and metabolites (DDTs) in marine sediments. Six 13C-labeled or deuterated PRCs were impregnated into polydimethylsiloxane (PDMS) fiber before use. Desorption of PRCs from PDMS fibers and absorption of DDTs from sediment were isotropic in a range of sediments evaluated ex situ under well-mixed conditions. When applied to a historically contaminated marine sediment from a Superfund site, the PRC-SPME method yielded Cfree values identical to those found by using a conventional equilibrium SPME approach (Eq-SPME), wherease the time for mixing was reduced from 9 d to only 9 h. The PRC-SPME method was further evaluated against bioaccumulation of DDTs by Neanthes arenaceodentata in the contaminated sediment with or without amendment of activated carbon or sand. Strong correlations were consistently found between the derived equilibrium concentrations on the fiber and lipid-normalized tissue residues for DDTs in the worms. Results from the present study clearly demonstrated the feasibility of coupling PRCs with SPME sampling to greatly shorten sampling time, thus affording much improved flexibility in the use of SPME for bioavailability evaluation. Environ Toxicol Chem 2013;32:1946–1953.

Evaluation of different methods for assessing bioavailability of DDT residues during soil remediation

“…The background levels of the 9 HOCs in soil C are given in Table S1, and were much lower than the spiked concentrations. The procedure used for spiking soil C followed a previous study (Bao et al, 2013). Briefly, 10 g of sand was uniformly spread on the bottom of 1.5 L glass jar and spiked with an acetone solution containing the 9 HOCs.…”

“…The glass jar was then rotated at 50 rpm for 2 weeks at room temperature. The C Total in the fieldcontaminated and spiked soils were measured after exhaustive solvent extraction (Bao et al, 2013) and are given in Table S4. The bouyoucos hydrometer method (Ashworth et al, 2001) was used to characterize the soil textures.…”

“…For example, for the mild solventextraction methods, the measurement invariably depends on the strength of the selected solvent and sometimes even the solventto-solid ratio (Mayer and Reichenberg, 2006), while Tenax sequential desorption is extremely time-consuming and tedious (Cui et al, 2013;Liu et al, 2011). Equilibrium samplers, such as SPME and PE, require equilibrium conditions, which may take weeks or even months to attain (Mayer et al, 2000;Bao et al, 2013). Therefore, a simple, rapid, and ready-to-use method is needed to accurately predict HOC bioavailability in soil.…”

“…Thus, a wide variety of chemically-based methods have been introduced to quantify HOC bioavailability in recent years. These methods include partial extraction-based methods, e.g., mild solvent extraction (Chung and Alexander, 1998;Tao et al, 2006), Tenax extraction (Cornelissen et al, 2001;You et al, 2011), hydroxypropyl-b-cyclodextrin (HPCD) extraction (Hartnik et al, 2008;Reid et al, 2000), and supercritical fluid extraction (SFE) (Kreitinger et al, 2007), and equilibrium sampling devices, e.g., solid phase microextraction (SPME) (Bao et al, 2013), polyethylene sampling device (PE) (Fernandez et al, 2009), and polyoxymethylene sampler (POM) (Endo et al, 2011;Muijs and Jonker, 2012). Many studies have attempted to demonstrate how these methods would provide a good prediction for the actual bioavailability of HOCs in sediments or soils.…”

Applications of Compound-Specific Isotope Analysis for Determining Persistent Organic Pollutant Origin, Transport and Transformation in the Aquatic Environment

“…While radio-isotope analysis applies an entirely different set of principles to the investigation of POPs, it is worth mentioning that controlled introductions of labeled DDT have generally been favored for experimental purposes . 69 Actual applications of stable-isotope principles to the determination of ambient sample DDT origins have been severely limited, with none performed to date with a focus on freshwater CSIA. Meanwhile, strong historical preference has been given to the established methods of isomer abundance ratio analysis for these purposes.…”