Development of an environmental friendly method for the analysis of organochlorine pesticides in sediments

This work proposes a pressurized hot water extraction (PHWE) followed by solid phase microextraction (SPME) and determination by gas chromatography-mass spectrometry method for the analysis of organochlorine pesticides in sediment samples. For SPME, extraction temperature and time, desorption temperature and desorption time, and effect of an organic modifier were studied. For PHWE, parameters such as organic modifier, percentage of organic modifier, temperature, and static extraction time were studied. When these parameters were selected, the figures of merit were calculated in order to assess the performance of the proposed method. Quantitative recoveries (80-115%) and satisfactory precisions were obtained. The detection and quantification limits were between 0.11 and 16 microg kg(-1) and between 0.24 and 22 microg kg(-1), respectively with good linearity between LOQs and 500 microg kg(-1) for most of the studied pesticides. The method was validated by the analysis of a reference marine sediment material (SRM 1944). The obtained results are in excellent agreement with the certificate material. Another sediment reference material (SRM 1941b), with a very low concentration of pesticides was also analyzed with good results. In addition, this method was successfully applied to the analysis of three marine sediment samples. The developed method seems to be a nearly full automated, environmental friendly, sensitive, simple and less-time consuming method. Moreover this method, look for the implementation of the principles of green analytical chemistry and has demonstrated to be suitable for the analysis of organochlorine pesticides at trace levels in environmental matrices as sediment samples.

A process for the purification of organochlorine contaminated activated carbon: Sequential solvent purging and reductive dechlorination

A system for the purification of organochlorine contaminated activated carbon is described. The system involves a continuous flow of aqueous ethanol to purge organochlorines from activated carbon. The organochlorine laden solvent is simultaneously treated with zero valent zinc as the bulk electron source, water as the proton source and the electron shuttle cyanocobalamin as a catalyst for reductive dechlorination. The system was characterised by performing batch reactions and extractions before being applied in a continuous flow system. In particular the ratio of water to ethanol in the system needed to be optimised. Water is needed for the reductive dechlorination reaction whilst it is not conducive to the extraction process. An 80% ethanolic solution was found to give optimal reductive dechlorination rates without compromising extraction of organochlorines from activated carbon. Of three electron shuttles evaluated cyanocobalamin was discovered to be the most relevant to the system with respect to reductive dechlorination rates and its ability to avoid absorption to activated carbon.

Detection method and toxicity study of a new disinfection by-product, 2,2,4-trichloro-5-methoxycyclopenta-4-ene-1,3-dione (TCMCD), in chlorinated drinking water

The detection method of 2,2,4-trichloro-5-methoxycyclopenta-4-ene-1,3-dione (TCMCD), a new disinfection by-product, was established and optimized. Drinking water samples from eight cities in Jiangsu Province, China, were analyzed and TCMCD was detected ranging from 42 to 171 ng/L among the water samples from the three cities. Toxicity of TCMCD was studied using the exposure of zebrafish and the human peripheral blood lymphocyte micronucleus assay. The results showed that TCMCD is fatal to zebrafish embryos and is a potential mutagen to human beings.

Biodegradation of 1,1,2,2-tetrachloroethane in Upflow anaerobic sludge blanket (UASB) reactor

This study examines the performance of bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactor in treating simulated wastewaters containing 1,1,2,2-tetrachloroethane (TeCA). Reactors R1 (control) and R2 (containing TeCA) were operated at Hydraulic Retention Times (HRTs) of 36, 30, 24, 18 and 12 h. The removal of TeCA decreased from 99.85% to 98.40% as the HRT was lowered down from 36 to 12 h. The maximum TeCA dechlorination rate and the half velocity coefficient were 0.2 d(-1) and 18.58 mg TeCA/l, respectively. The Organic Loading Rate (OLR) was varied from 1.5 to 3.1 kg/m(3)/d to yield various substrate:co-substrate ratios and the overall removal of TeCA throughout this study was more than 99%. The average effluent TeCA concentration at optimum HRT (24 h) and substrate:co-substrate ratio (100:1) was less than 0.1 mg/l. The granules within the reactor were 0.1-3.2 mm in size with a heterogeneous bacterial population.

Method for the determination of selected organochlorine pesticides and polychlorinated biphenyls in human serum based on a gel permeation chromatographic clean-up

A gel permeation chromatographic (GPC) clean-up based method was developed for determination of selected organochlorine pesticides and polychlorinated biphenyls in human serum. The method permits automation of the sample extract clean-up stage and is designed to work with small amounts of sample. Different working variables were studied in its development, including injection volume, flow rate, and fat amount as the most representative coextract. The method provides solvent and time savings. Initial extraction was performed using 96-well solid-phase disk extraction plates, and quantification was performed by gas chromatography with electron capture detection and mass spectrometry. Recoveries of PCB congeners 28, 52, 101, 118, 138, 153, and 180 and organochlorine pesticides HCB, beta-HCH, gamma-HCH, heptachlor epoxide, p,p'-DDE, and p,p'-DDT at two spiking levels ranged from 55% to 115% with relative standard deviations ranging from 2.0% to 14.6%. Limits of quantification ranged from 0.06 to 0.16 ng mL(-1) for PCBs and from 0.12 to 0.36 ng mL(-1) for organochlorine pesticides. Finally, the method was applied to the analysis of 38 serum samples and the results were compared with those of another procedure validated at the laboratory.

Airborne chloronaphthalenes in Scots pine needles of Poland

The amounts, profiles and origin of CNs (from triCNs to octaCN) sequestered in Scots pine needles collected from 25 spatially distant sites in Poland have been studied based on congener-specific data obtained after a several clean-up and fractionation steps and final HRGC/HRMS separation and determination. The absolute concentrations of CNs varied largely from site to site, i.e., by 15-fold. The sum of tri- to octaCN concentration at fifteen of the least contaminated sites ranged from 70 to 280 pg g(-1) ww, and at further eight sites were from 340 to 540 pg g(-1) ww, while at two the most contaminated were 1000 and 1100 pg g(-1)ww. There were some substantial similarities but also variations in triCN to octaCN homologue group profiles depending on the site. Among triCNs the isomers such as 1,2,4-/1,3,7-/1,4,6-triCNs (nos. 14/21/24) dominate in Scots pine needles. For majority of the sites examined 1,2,4-/1,3,7-/1,4,6-triCNs are also the major contributors to the bulk of CNs determined. Among tetraCNs isomer 1,2,5,8-tetraCN (no. 38) was dominant contributor at eighteen sites, while 1,2,4,6-/1,2,4,7-/1,2,5,7-tetraCN (nos. 33/34/37) at seven other sites. In the case of pentaCNs isomer 1,2,4,5,8-pentaCN (no. 59), was dominant contributor alone. Octachloronaphthalene frequently contributed substantially to the bulk of CNs. The Cluster Analysis and Principal Component Analysis did indicate that the compositional profiles of CNs found in Scots pine needles resemble somehow these found in the bottom ashes after coke and coal burning as well as of Halowax 1000 and 1099 formulations.

Determination of semi-volatile organochlorine compounds in the atmosphere of Singapore using accelerated solvent extraction

Accelerated solvent extraction (ASE) has been applied to the quantitative extraction of organochlorine compounds (OCs), including organochlorine pesticides (HCHs, DDXs) and polychlorinated biphenyls (PCBs) present in both atmospheric particulate and gaseous phase. Extraction parameters such as the combination of solvents, extraction temperature, and static extraction time were investigated and optimized. Effective extraction can be carried out using a 3:1 mixture of n-hexane and acetone as extraction solvents at 100 degrees C in 20min for all the compounds studied. The entire analytical procedure developed in this study proves to be reliable as evident from the analysis of specific surrogate standards with the mean recoveries per sample being greater than 82%. The optimized method was validated using NIST-certified SRM 1649a. Semi-volatile OCs, in the atmosphere of Singapore were quantified using the optimized ASE method together with GC-MS. Total average concentrations of SigmaHCHs, SigmaDDXs, and SigmaPCBs in air samples were 244.9+/-88.5pgm(-3), 7.7+/-4.1pgm(-3), and 34.1+/-19.7pgm(-3), respectively. The distribution of these compounds between the gas and particulate phase is discussed. Possible sources of atmospheric OCs are evaluated based on the molecular ratio of specific compounds and backward air trajectory analysis.

Organochlorine pesticides levels in Portuguese coastal areas

Data on levels of persistent organochlorine pesticides (OCPs) that exhibit potentially harmful effects to the environment all over the Portuguese coastal sediments were scarce. Therefore, in 2007-2008 12 OCPs were surveyed in surface sediments from 11 coastal sites (estuarine or lagoonal) covering north, centre and south areas of Portugal. Analyzes were performed using a previously validated method, involving pre-extraction of OCPs from sediments assisted by microwave and headspace solid-phase microextraction followed by gas chromatography with electron capture detection for quantification and mass spectrometry for OCPs identification. Measurable levels (0.08-26ng g(-1)) of alpha-hexachlorocyclohexane (alpha -HCH), gamma-hexachlorocyclohexane (lindane), aldrin, dieldrin, endrin, 4,4'-DDT, 4,4'-DDD, 4,4'-DDE, heptachlor, heptachlor epoxide, endosulfan I and methoxychlor were observed in all cases. In few cases, the found levels denote the probability of occurrence of adverse biological effects.

Solvent extraction of chlorinated compounds from soils and hydrodechlorination of the extract phase

The remediation of soils contaminated with chlorinated compounds was investigated. The process consists of solvent extraction followed by catalytic hydroprocessing (hydrodechlorination) of the extract phase. A mixture of ethylacetate-acetone-water (E-A-W) was adopted as solvent in the extraction process. Tests of extraction of chlorobenzene from a model contaminated soil were carried out and the Langmuir adsorption equation was characterized. The solvent, contaminated with different chlorinated compounds was then hydrotreated with a Pd/C catalyst. The chlorinated compounds tested are: chlorobenzene, hexachlorobenzene and hexachloroethane at various initial concentrations. The reaction runs were carried out at room temperature and at a hydrogen pressure of 1bar. Hydrotreating of these compounds takes place according to a Langmuir-Hinshelwood mechanism whose kinetic parameters were determined. The experiments show that high destruction efficiencies may be reached in reasonably short times, particularly for hexachloroethane. Longer times are necessary for the aromatic compounds (chlorobenzene and hexachlorobenzene) for which the CCl bond is much stronger than that in the aliphatic compound. Time for a 95% destruction efficiency for all experimental runs was determined. A noteworthy finding is that ethylacetate and acetone do not undergo any reaction during hydrotreating. Thus the treated extract solution may be recycled inasmuch as it conserves its full extracting capacity towards chlorinated compounds. A limitation in recycling is the inhibiting effect of benzene on the HDCl rate: benzene produced by HDCl of chlorinated compounds, accumulates in the solvent mixture in the event of recycling. Simulation of the process with the recycling of the solvent was carried out, accounting for the inhibiting effect of benzene.

Density functional theory studies of chloroethene adsorption on zerovalent iron

Adsorption of perchloroethene (PCE), trichloroethene (TCE), and cis-dichloroethene (cis-DCE) on zerovalent iron is investigated using density functional theory (DFT) to evaluate hypotheses concerning the relative reactivity of these compounds on zerovalent iron. Four different chloroethene adsorption modes on the Fe(110) surface were studied using periodic DFT and the generalized gradient approximation (GGA). Of the adsorption sites examined, the atop site, where the chloroethene C==C bond straddles a surface iron atom, was the most energetically favorable site for the adsorption of all three chloroethenes. Electronic structure and property analyses provide an indication of the extent of sp2-sp3 hybridization. The strong hybridization of the pi-bonding orbital between the chloroethene C==C bond and the iron surface suggests that adsorbed chloroethenes are strongly activated on Fe(110) and are likely precursors for subsequent chloroethene dissociation on the Fe surface. When the effect of solvation is indirectly taken into account in the DFT simulations by considering the hydration energies of chloroethenes in bulkwater,the ordering ofthe adsorption energies of chloroethenes from the aqueous phase onto Fe(110) is in agreement with experimental observation (PCE > TCE > cis-DCE). Electronic properties of the adsorbed configurations of chloroethenes are also presented.

Photo-electrochemical degradation of some chlorinated organic compounds on n-TiO2 electrode

The electrolysis of some chlorinated organic compounds such as chloroacetic acids, chloromethanes and chloroethenes were carried out on a photo-irradiated n-TiO(2) electrode applied a constant potential, 1.0 V vs. Ag/AgCl, and the alternated pulse potentials of +1.0 V and various negative potentials, -1.0, -1.2 and -1.4V vs. Ag/AgCl in 0.1 mol dm(-3) Na(2)SO(4) solutions saturated with oxygen or with nitrogen. These compounds were degraded on the n-TiO(2) electrode by the photo-electrolysis and mineralized to carbon dioxide, carbon monoxide and chloride ion. When the alternated pulse potentials were applied, the mineralization yields were increased for these compounds, especially for trichloroacetic acid and carbon tetrachloride, both of which were comparatively stable to the degradation in the constant potential electrolysis. The presence of oxygen in the solution was effective for the mineralization of these compounds, while little effective for that of trichloroacetic acid and of carbon tetrachloride.

Equilibrium sampling: partitioning of organochlorine compounds from lipids into polydimethylsiloxane

Polydimethylsiloxane (PDMS) can be used for equilibrium sampling of environmental pollutants in a large variety of matrices including biota. For comparison with lipid-normalized concentrations e.g. from biota monitoring programmes, reliable lipid to PDMS partition ratios (K(Lipid,PDMS)) are required. Additionally, K(Lipid,PDMS) facilitate comparison of equilibrium sampling data obtained in various environmental media and can be helpful to convert equilibrium sampling data into a more informative form. This work investigated the equilibrium partitioning of polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) between lipids from biota of different trophic levels and PDMS. One vegetable oil, a fish oil and seal oil were investigated. The lipid to PDMS partition ratios were compound-specific and ranged from 14.5 to 62.9 g/g with correction for lipid uptake into the PDMS and from 13.0 to 54.8 g/g without correction. Additionally, PDMS served as a reference partitioning phase for the accurate determination of lipid to lipid partition ratios, which for all analytes were close to unity. Evaluating the results in a bioaccumulation context, they indicate that the equilibrium partitioning of neutral lipophilic environmental contaminants into the lipids of the three investigated species will be very similar, although they represent three distinct trophic levels.

[Determination of organochlorine pesticides in soils using gas chromatography-tandem mass spectrometry]

A method was developed for the determination of organochlorine pesticides (OCPs) in soils using accelerated solvent extraction (ASE, Florisil cleanup in the extraction cell) and gel permeation chromatography (GPC) on-line concentration prior to the determination by ga chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). And then 20 agricultural soil samples in Shanghai suburbs were determined. Multiple reaction monitoring (MRM) was applied to qualify and quantify the target compounds. In the different linear ranges (included in 0.001 - 0.2 mg/L) of each pesticide, the correlation coefficients were higher than 0.995. The average recoveries in spiked soils were 65.9% - 140.0% with the relative standard deviations of 1.5% - 20.3% (n = 5). The limits of detection (LOD) (S/N = 3) for these pesticides were from 0.1 to 3.0 microg/kg and the limits of quantification (LOQ) (S/N = 10)were from 0.3 to 8.0 microg/kg. Among these soils, hexachlorocyclohexane (HCHs) and hexachlorobenzene (HCB) were detected little with a content ranges of 1.82 - 3.70 and 0.94 -9.8 microg/kg, respectively. DDTs (including 2-(2-chlorophenyl)-2-(4-chloropenyl) -1,1,1-trichloroethane (p, p'-DDT), 2,2-bis (4-chlorophenyl)-1,1-dichloro-ethylene (p,p'-DDE), 2,2-bis (4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD)) were found widely with a range of 1.08 - 308.76 microg/kg and mean value of 53.28 microg/kg. The content ratio of DDT/( DDE + DDD) were less than 1.0 in 85% soil samples, indicating that DDT might come from the early days.

Lynamicins A-E, chlorinated bisindole pyrrole antibiotics from a novel marine actinomycete

A series of chlorinated bisindole pyrroles, lynamicins A-E (1-5), was discovered from a novel marine actinomycete, NPS12745, which was isolated from a marine sediment collected off the coast of San Diego, California. Close to full length 16S rRNA sequence analysis indicated that NPS12745 is a novel strain of a recently described marine actinomycete with the proposed genus name Marinispora. The antimicrobial spectrum of these compounds was evaluated against a panel of 11 pathogens, which demonstrated that these substances possess broad-spectrum activity against both Gram-positive and Gram-negative organisms. Significantly, compounds 1-5 were active against drug-resistant pathogens such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium.

[Analysis of organochlorine pesticides in buckwheat using pressurized liquid extraction and gas chromatography]

Seven organochlorine pesticides (OCPs) in buckwheat were extracted by a homemade 24 cells auto-pressurized liquid extraction instrument (APLE) and then analyzed by gas chromatography with electronic capture detection. The optimal extraction condition was found to be 100 degrees C and 10 MPa for 5 min with acetone/n-hexane (1:1, v/v) as the extraction solvent. The extraction was performed twice for each sample to obtain complete extraction. The buckwheat was mixed with florisil and active carbon before filling into extraction cells. Concentrated sulfuric acid was used in clean up step of the extractant. The standard mixture of OCPs including alpha-benzene hexachloride (BHC), gamma-BHC, delta-BHC, p, p'-dichloro-diphenyl-dichloroethylene (p,p'-DDE), p,p'-dichloro-diphenyl-dichloroethane (p, p'-DDD), o, p-dichloro-diphenyl trichloro-ethane (o,p-DDT), p,p'-DDT was used for the identification and quantification in gas chromatographic analysis. The absolute recoveries of the 7 organochlorine pesticides were between 68%-126% with the relative standard deviations lower 14.7%. The detection limits were between 0.051 - 0.18 ng/g. The relative recoveries were as high as 116%-148% compared with Soxhlet extraction. It shows that the recoveries of APLE are much better than Soxhlet extraction, and the time of extraction for APLE is only about 15 min which is much less than conventional extraction methods.

Chlorocyclinones A-D, chlorinated angucyclinones from Streptomyces sp. strongly antagonizing rosiglitazone-induced PPAR-gamma activation

In the course of our screening to identify novel PPAR-gamma modulators for the potential treatment of type 2 diabetes, four new chlorinated angucyclinones, chlorocyclinones A-D ( 1- 4), were isolated from the mycelium of Streptomyces sp. strain DSM 17045. Their structures were established by spectroscopic methods. Chlorocyclinones antagonize rosiglitazone-induced peroxisome proliferator-activated receptor gamma (PPAR-gamma) activation with IC 50's < 0.4 microM in vitro using an AlphaScreen assay and are able to displace rosiglitazone from the PPAR-gamma ligand-binding domain (LBD) in a scintillation proximity assay (SPA). The compounds proved to be active in a cell-based reporter gene assay as well, antagonizing rosiglitazone-induced PPAR-gamma activity with IC 50 values between 0.60 and 7.0 microM. Chlorocyclinone C ( 3) exhibited the most potent activity in all assays.

Organochlorine Pesticides in Placentas from Southern Spain and Some Related Factors

During pregnancy, lipophilic xenobiotics stored in maternal adipose tissue can be mobilized and enter her blood circulation and reach the placenta. This study measured residues of oestrogen-mimicking organochlorine pesticides (OCs) in 150 placenta samples from women in Southern Spain. OCs were extracted from placenta by solid-liquid technique and purified by preparative liquid chromatography. Gas chromatography/electron-capture detection and mass spectrometry were used to identify and quantify p,p'-DDT and congeners/metabolites, endosulphan and congeners/metabolites, lindane, aldrin/dieldrin/endrin, hexachlorobenzene, methoxychlor and mirex. A mean of eight pesticides per placenta were detected (range, 3-15 pesticides). Endosulphan-ether, endosulphan-diol, endosulphan-I, p,p'-DDE, o,p'-DDD, p,p'-DDT, o,p'-DDT and lindane were detected in >or=50% of samples; p,p'-DDE was the most frequent (96.03%), followed by endosulphan-diol (76.86%) and lindane (74.17%). Presence of more pesticides was significantly associated with lower birth weight. Mean concentration of p,p'-DDE was 2.37+/-2.80 ng/g of placenta or 76.62+/-104.85 ng/g of lipid. Higher maternal body mass index was significantly associated with higher endosulphan concentrations in placenta, and greater maternal weight gain was significantly associated with higher p,p'-DDE concentrations. Prenatal exposure to OC xenoestrogens may be a causative factor in adverse reproductive health trends, and further studies are required to identify and describe pathways of this exposure to enhance preventive measures.

Carbamidocyclophanes A-E, chlorinated paracyclophanes with cytotoxic and antibiotic activity from the Vietnamese cyanobacterium Nostoc sp

Five new paracyclophanes, carbamidocyclophanes A-E (1-5), characterized by carbamido side chains at a symmetric [7.7]paracyclophane ring, have been isolated from the biomass of the Vietnamese Nostoc sp. CAVN 10. Structure elucidation by spectroscopic methods showed that 1-5 vary in the substitution pattern of the chlorinated butyl side chains. The compounds exhibited cytotoxic activity against MCF-7 (breast cancer cell line) and Fl cells (human amniotic epithelial cell line) and moderate antibacterial activity against the Gram-positive bacterium Staphylococcus aureus.

Persistent organic pollutants (POPs) in the conventional activated sludge treatment process: model predictions against experimental values

The FATE and treatibility estimator (FATE) model, developed by the United States Environmental Protection Agency was used for the prediction of the FATE of 26 persistent organic pollutants (POPs), i.e. 7 PCBs and 19 organochlorine compounds (OCs), during the conventional activated sludge treatment process applied in the waste water treatment plant (WWTP) of Thessaloniki, Greece. The removal rates predicted by the model for the primary and the secondary treatment stages were found to differ substantially from those experimentally measured. When the overall treatment was considered, the differences between measured and model predicted removals were within acceptable limits of confidence. Possible reasons that might cause deviations from experimental values were suggested to be the wastewater content in dissolved organic carbon (DOC), and/or the low concentrations of POPs in untreated wastewater.

A new chloro-monoterpene from the mangrove endophytic fungus Tryblidiopycnis sp. (4275)

A new chloro-monoterpene (compound 1) and three known compounds, peroxyergosterol, uracil and methylisocoumarin, were isolated from the ethyl acetate extract of the fermentation broth of the mangrove endophytic fungus Tryblidiopycnis sp. (4275) obtained from Kandelia woody tissue from Mai Po, Hong Kong. Its structure was determined spectroscopically and by X-ray crystallographic analysis.

A simple and fast extraction method for organochlorine pesticides and polychlorinated biphenyls in small volumes of avian serum

A solid-phase extraction (SPE) method was developed using 8M urea to desorb and extract organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) from avian serum for analysis by capillary gas chromatography with electron capture detection (GC-ECD). The analytes were efficiently extracted from the denatured serum-lipoprotein-analyte complex by one passage through an Oasis((R)) hydrophilic-lipophilic-balanced (HLB) SPE cartridge. No further clean-up was necessary, the entire extraction procedure and GC-ECD analysis can be accomplished in less than 3h. Serum volumes ranged from 100 microL to 1 mL with absolute recoveries of 90-101% for PCBs and 74% to 101% for the OC pesticides.

Use of polyoxyethylene surfactants for the extraction of organochlorine pesticides from agricultural soils

Two non-ionic surfactant mixtures (POLE and Polyoxyethylene 10 Cetyl ether, POLE and Polyoxyethylene 10 Stearyl ether) have been used for microwave-assisted extraction of six organochlorine pesticides from agricultural soils prior to being determined by HPLC-UV. An experimental design was applied for the determination of variables which affect to recovery and to optimize the extraction parameters, surfactant concentration and volume, microwave time and power. Under the optimized conditions, the method was applied to different soil samples in order to analyze the influence of soil characteristics on the pesticides extraction. The results obtained indicate that most of these compounds can be recovered in good yields with RSD lower than 10% and detection limit ranged between 80 and 800 ng g(-1) for the pesticides studied. The proposed method was applied to a reference soil sample and to aged soils.

Combined removal of chlorinated ethenes and heavy metals by zerovalent iron in batch and continuous flow column systems

The combined removal of chlorinated ethenes and heavy metals from a simulated groundwater matrix by zerovalent iron (ZVI) was investigated. In batch, Ni (5-100 mg L(-1)) enhanced trichloroethene (TCE, 10 mg L(-1)) reduction by ZVI (100 g L(-1)) due to catalytic hydrodechlorination by bimetallic Fe0/Ni0. Cr(VI) or Zn (5-100 mg L(-1)) lowered TCE degradation rates by a factor of 2 to 13. Cr(VI) (100 mg L(-1)) in combination with Zn or Ni (50-100 mg L(-1)) inhibited TCE degradation. Addition of 20% H2(g) in the headspace, or of Zn (50-100 mg L(-1)), enhanced TCE removal in the presence of Ni and Cr(VI). Sorption of Zn to ZVI alleviated the Cr(VI) induced inhibition of bimetallic Fe0/Ni0 apparently due to release of protons necessary for TCE hydrodechlorination. In continuous ZVI columns treating tetrachloroethene (PCE, 1-2 mg L(-1)) and TCE (10 mg L(-1)), and a mixture of the metals Cr(VI), Zn(II), and Ni(II) (5 mg (L-1)), the PCE removal efficiency decreased from 100% to 90% in columns operated without heavy metals. The PCE degradation efficiency remained above 99% in columns receiving heavy metals as long as Ni was present. The findings of this study indicate the feasibility and limitations of the combined treatment of mixtures of organic and inorganic pollutants by ZVI.

Headspace Solid Phase Micro Extraction GC-ECD Determination of Volatile Organic Chlorinated Hydrocarbons in Soils

Soil samples were suspended in a suitable aqueous solvent and a solid phase microextraction (SPME) fibre was used to sample the headspace (HS) for five volatile chlorinated compounds (VOX). Their determination was made by GC-ECD technique in the splitless mode. Preliminary studies on the effects of methanol and of the sand/clay ratio on the fibre extraction were made. Four experimental factors, namely, extraction time, extraction temperature, pH and NaCl%, able to affect distribution of the analytes among the four different phases, were varied in suitable ranges. A multivariate approach applied to the face centred cube (FCC) experimental design, was used to try to optimise the overall sample response. The suitable set of factors found for the determination of chloroform, 1,2-dichloroethane, trichloroethylene, 1,1 ,2-trichloroethane, 1,1,2,2-tetrachloroethane, was a compromise among the relevant optimal factor sets of the single analytes. Detection limits of 0.003 ng, 0.022 ng, 0.001 ng, 0.015 ng and 0.002 ng were found respectively for the five cited analytes. The method was successfully used to determine the analyte contents in two real soils sampled in an industrial area.

Study on the structure and mutagenicity of a new disinfection byproduct in chlorinated drinking water

The structure of a new chlorinated disinfection byproduct (DBP) in drinking water is studied. The new DBP was prepared through chlorinating its best precursor, and it was extracted and isolated from the chlorination products. Its structure is identified as 2,2,4-trichloro-5-methoxycyclopent-4-ene-1,3-dione (TCMCD) through FTIR, MS, 1H NMR, and 13C NMR spectroscopic analysis and single-crystal X-ray diffraction method. Results of the Ames test with tester strain TA100 indicated that the newly identified DBP TCMCD is a mutagen.