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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 (13) C-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), whereas 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.

SUBMITTER: Bao LJ

PROVIDER: S-EPMC3899093 | biostudies-other | 2013 Sep

REPOSITORIES: biostudies-other

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

Bao Lian-Jun LJ Jia Fang F Crago J J Zeng Eddy Y EY Schlenk D D Gan Jay J

Environmental toxicology and chemistry 20130719 9

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 metabo ...[more]

PMID: 23661411

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Project description:BackgroundNon-invasive diagnostic strategies aimed at identifying biomarkers of cancer are of great interest for early cancer detection. Urine is potentially a rich source of volatile organic metabolites (VOMs) that can be used as potential cancer biomarkers. Our aim was to develop a generally reliable, rapid, sensitive, and robust analytical method for screening large numbers of urine samples, resulting in a broad spectrum of native VOMs, as a tool to evaluate the potential of these metabolites in the early diagnosis of cancer.MethodsTo investigate urinary volatile metabolites as potential cancer biomarkers, urine samples from 33 cancer patients (oncological group: 14 leukaemia, 12 colorectal and 7 lymphoma) and 21 healthy (control group, cancer-free) individuals were qualitatively and quantitatively analysed. Dynamic solid-phase microextraction in headspace mode (dHS-SPME) using a carboxen-polydimethylsiloxane (CAR/PDMS) sorbent in combination with GC-qMS-based metabolomics was applied to isolate and identify the volatile metabolites. This method provides a potential non-invasive method for early cancer diagnosis as a first approach. To fulfil this objective, three important dHS-SPME experimental parameters that influence extraction efficiency (fibre coating, extraction time and temperature of sampling) were optimised using a univariate optimisation design. The highest extraction efficiency was obtained when sampling was performed at 50°C for 60 min using samples with high ionic strengths (17% sodium chloride, w v(-1)) and under agitation.ResultsA total of 82 volatile metabolites belonging to distinct chemical classes were identified in the control and oncological groups. Benzene derivatives, terpenoids and phenols were the most common classes for the oncological group, whereas ketones and sulphur compounds were the main classes that were isolated from the urine headspace of healthy subjects. The results demonstrate that compound concentrations were dramatically different between cancer patients and healthy volunteers. The positive rates of 16 patients among the 82 identified were found to be statistically different (P<0.05). A significant increase in the peak area of 2-methyl-3-phenyl-2-propenal, p-cymene, anisole, 4-methyl-phenol and 1,2-dihydro-1,1,6-trimethyl-naphthalene in cancer patients was observed. On average, statistically significant lower abundances of dimethyl disulphide were found in cancer patients.ConclusionsGas chromatographic peak areas were submitted to multivariate analysis (principal component analysis and supervised linear discriminant analysis) to visualise clusters within cases and to detect the volatile metabolites that are able to differentiate cancer patients from healthy individuals. Very good discrimination within cancer groups and between cancer and control groups was achieved.

Project description:Pharmaceutical compounds are emerging contaminants in aquatic environment due to their massive use (human and veterinary medicines, agriculture and aquaculture) and a limited removal by waste water treatment plants (WWTPs). In this work, a representative determination of ecotoxicological potential of two different NSAIDs compounds was studied in the sensitive bioindicator marine organism M. Galloprovincialis. Mussels were exposed, under regulated laboratory conditions, to Ketoprofen (KET) and Nimesulide (NIM), dosed alone at the realistic environmental concentration of 0.5Âµg/L for 14 days. Gene expression analyses of Mytilus galloprovincialis exposed to KET and NIM have been performed through a DNA microarray platform. Mussels Mytilus galloprovincialis (5 Â± 1 cm shell length) were obtained from a local farm (Numana, Ancona) and acclimatized for 10 days to laboratory conditions with aerated seawater, at 18 Â± 1 Â°C, 37 â?° salinity, pH 7.5 Â± 0.5 and oxygen saturation >94%. Mussels were distributed into three 17 L aquarium and exposed at 0.5Âµg/L to ketoprofen (KET) and nimesulide (NIM) dosed alone for 14 days. All treatments were compared to control (CTRL) containing 0.00001% of methanol. Water was changed every other day and concentration of molecules were restored. Gene transcription analyses of 12 digestive glands pools (four pools for each treatment composed by 3 digestive glands; CNTR, NIM and KET) were performed using a 8X60K Agilent oligo-DNA microarray platform GPL18667. Microarrays were synthesized in situ using the Agilent non-contact ink-jet technology including default positive and negative controls. Total RNA was isolated using Extract-all (Eurobio) procedure. RNA quality and integrity was controlled on the Agilent bioanalyzer using RNA nanochips and Agilent RNA 6000 nanoreagents (Agilent Technologies, Waldbronn, Germany). RNA concentrations were measured at 260 nm using a ND-1000 spectrophotometer (Nanodrop Technologies) using the conversion factor 1 OD = 40 mg/mL total RNA. Samples were stored at -80Â°C until further use. Gene expression profiling was performed using an Mytilus galloprovincialis oligo-DNA microarray of 59,971 probes based on single-colour detection (Cyanine-3 only). Microarrays were scanned with Agilent scanner G2565BA at a resolution of 2 microns; all slides were scanned twice at two different sensitivity settings (XDRHi 100% and XDRLo 10%); the scanner software created a unique ID for each pair of XDR scans and saved it to both scan image files. FeatureExtraction v10.7.3.1 used XDR ID to link the pairs of scans together automatically when extracting data. The signal left after all the FE processing steps have been completed is ProcessedSignal that contains the Multiplicatively Detrended, Background-Subtracted Signal.

Dataset Information

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

Publications

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

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