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*Cutter, S. L., Heppell, C. M., and Spencer, K. L. Department of Geography, Queen Mary, University of London, Mile End Road, London, E1 4NS England. *

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Presentation on theme: "*Cutter, S. L., Heppell, C. M., and Spencer, K. L. Department of Geography, Queen Mary, University of London, Mile End Road, London, E1 4NS England. *"— Presentation transcript:

1 *Cutter, S. L., Heppell, C. M., and Spencer, K. L. Department of Geography, Queen Mary, University of London, Mile End Road, London, E1 4NS England. * Corresponding author +44 (0) Carey, P.J. Centre for Contaminated Land Remediation School of Science University of Greenwich at Medway Chatham Maritime Kent ME4 4TB England. Investigation of organic contaminants in the Medway and Seine estuaries Accelerated Solvent Extraction (ASE) - GC/MS for organochlorine pesticide extraction, cleanup and analysis. A fully automated Dionex ASE 200 system has been used. This system works by pumping a solvent into the top of an extraction cell, which contains the sample and any in-cell cleanup options. The cell is bought to elevated pressure and temperature within the oven then the extract is forced out of the bottom of the cell and collected in a vial for additional cleanup if necessary. Further work To continue method development for analysis of both OCLs and contemporary herbicides. Analysis of Medway and Seine surface and core samples by ASE method with the selected cleanup. Analysis of Medway and Seine surface samples by selected MASE method. References Abrha, Y. and Raghaven, D., Polychlorinated biphenyl (PCB) recovery from spiked organic matrix using accelerated solvent extraction (ASE) and Soxhlet extraction. Journal of hazardous materials, B80, Bandh, C., Bjorklund, E., Mathiasson, L., Naf, C., Zebuhr,Y., Comparison of Accelerated Solvent Extraction and Soxhlet Extraction for the determination of PCBs in Baltic Sea sediments. Environmental science and technology, 34, Canadian Council of Ministers of the Environment, Canadian Environmental Quality Guidelines. Cundy, A. B., Hopkinson, L., Lafite, R., Spencers, K., Taylor, J.A., Ouddane, B., Heppell, C. M., Carey, P. J., Charman, R., Shell, D. and Ullyott, S. Heavy metal distribution and accumulation in two Spartina sp.-dominated macrotidal salt marshes from the Seine estuary (France) and the Medway estuary (U.K.). Dionex. Extraction of Chlorinated Pesticides using Accelerated Solvent Extraction (ASE). Application Note 320. Dionex, Selective extraction of PCBs from fish tissue using Accelerated Solvent Extraction (ASE). Application Note 322. Eskilsson, C. S. and Bjorklund E., Analytical-scale microwave-assisted extraction. Journal of Chromatography A, 902, Ganzler, K., Salgo, A., Valko, K., A novel sample preparation method for chromatography. Journal of Chromatography A, 371, Gomez-Ariza, J.L., Bujalance, M., Giraldez, I., Velasco, A., Morales, E., Determination of polychlorinated biphenyls in biota samples using simultaneous pressurized liquid extraction and purification. Journal of Chromatography A, 946, Hubert, A., Wenzel, K., Manz, M., Weissflog, L., Engewald, W., Schuurmann, G., High extraction efficiency for POPs in real contaminated soil samples using Accelerated Solvent Extraction. Analytical Chemistry, 72, 6, Jayaraman, S., Pruell, R. J., McKinney, R., Extraction of organic contaminants from marine sediments and tissues using microwave energy. Chemosphere, 44, Lopez-Avila, V., Sample preparation for environmental analysis. Critical Reviews in Analytical Chemistry, 29, 3, Sandy, C., Analysis of Organochlorine Pesticides and PCBs using SIM mode GC-MS and Large-Volume Injection. Agilent Technologies UK Ltd. Shen, G. and Lee, H. K., Determination of triazines in soil by microwave-assisted extraction followed by solid-phase microextraction and gas chromatography-mass spectrometry. Journal of Chromatography A, 985, Smith, R. M., Before the injection-modern methods of sample preparation for separation techniques. Journal of Chromatography A, 1000, Acknowledgements The authors would like to thank Intereg II for funding this research. Overall aim To investigate the nature and extent of organic contamination in sediments from the Medway and Seine estuaries. Objectives 1)To identify the nature and extent of Organochlorine (OCL) contamination in surface & sub-surface sediments. 2)To identify the nature and extent of selected contemporary herbicides in surface sediments. 3)To identify key priority organic pollutants for further study. Introduction/Rationale Sediment samples were collected from the Medway and Seine estuaries in order to investigate organic contamination as part of the Rives Manche Estuarine Watch (RIMEW) project. These estuaries represent very different estuarine environments. The Medway receives moderate contaminant inputs and has a low sedimentation rate thus is sediment starved. In contrast, the Seine is heavily contaminated as a result of its intense industrial focus and is subject to high sedimentation rates and infilling. Figure 1: Site locations. Cundy et al., Accelerated Solvent Extraction (ASE) and Gas Chromatography/ Mass Spectrometry is being used in this study for the investigation of historical organochlorine (OCL) contamination in the Seine and Medway estuaries. Historical OCL Pesticides under investigation are aldrin, dieldrin, DDT and its metabolites, endrin and lindane. They are stable, environmentally persistent and damaging pollutants. Important progress has been made over the last decade in the development of faster, safer and more environmentally friendly extraction and cleanup techniques for preparation of environmental samples for analysis (Lopez-Avila, 1999). Traditionally pesticide extractions were performed using Soxhlet extraction. Microwave Assisted Solvent Extraction (MASE), Supercritical Fluid Extraction (SFE) and Ultrasonic Extraction are alternative techniques that can be used. ASE also known as Pressurised Fluid Extraction (PFE) is a procedure that uses elevated pressures (1500 psi) and temperatures (100°C) to extract water soluble semivolatile organic compounds from a range of environmental media (USEPA, 1996). It has been trialed in this study for the extraction of OCLs due to its perceived advantages over alternative methods : ASE offers opportunities for in-cell cleanup techniques. ASE considerably reduces solvent usage. Soxhlet extraction can use from 250ml to 500ml of solvent. ASE reduces extraction times, a 10g soil sample can be extracted in approximately 12 minutes using 15ml of solvent (Dionex, application note 320). Sonication requires multiple washing procedure. Although ASE has been used for the extraction of a range of compounds from a variety of matrices (Bandh et al., 2000; Abrha and Raghavan, 2000; Hubert et al., 2000; Gomez-Ariza et al., 2002), its use on OCLs in estuarine sediments, with in-cell sample clean up, has been more limited. Microwave Assisted Solvent Extraction (MASE) and Liquid Chromatography/Mass Spectrometry with online Solid Phase Extraction (SPE-LC/MS n ) is being used for the analysis of contemporary herbicides. Contemporary herbicides under investigation are atrazine, Irgarol, simazine, isoproturon, diuron and selected metabolites. They are not as environmentally persistent as their predecessors, but their enhanced solubility means that they can easily reach surface and groundwaters. MASE is a well-established sample preparation technique with high recovery rapid extraction of the contemporary herbicides of interest. Microwaves were first used in laboratories in 1975 for the analysis of metals from biological samples and since then many different methods have been developed for a variety of samples. In 1986, Ganzler et al. used this technique to extract organic compounds from solid matrices. Steinheimer 1993 used this method to extract atrazine from soils and water samples (Eskilsson and Bjorklund, 2000). LC/MS n has been recently developed for the analysis of more soluble herbicides. During this procedure sample is placed into a closed vessel with a microwave absorbing solvent and irradiated with microwave energy. The energy heats the solvent which is in contact with the sample in order to partition analytes from the sample matrix into the solvent (Eskilsson and Bjorklund, 2000). Advantages of MASE include: Multiple samples can be extracted simultaneously. Elevated Temperatures (Eskilsson and Bjorklund, 2000). Reduced extraction times (15-30 min) compared with Soxhlet, Sonication and Supercritical Fluid Extraction (SFE) (Jayaraman et al., 2000). Low solvent volumes (10-30ml), about 10 times smaller than conventional techniques (Eskilsson and Bjorklund, 2000). More efficient than conventional techniques (Ganzler and Salgo, 1986 in Shen and Lee, 2003). Disadvantages: It uses a single extraction vessel, which needs to cool before filtration this can cause re-adsorption issues (Smith, 2003). Microwave absorbing solvents required. Environment agency data for Endrin Figure 2: Endrin concentrations in Medway estuary sediments (  g/kg) and the Marine Interim Sediment Quality Guideline (ISQG) for endrin from the Canadian Environmental Quality Guidelines. Note from figure 2 that the average sediment concentrations of Endrin at each site are above the Canadian ISQG. Due to these high concentrations further investigation of such compounds is necessary. None however exceed the Probable Effect Level (PEL) of 62.4  g/kg. In this study alumina cleanup has been trialed both in-cell and post-extraction to compare the recovery efficiencies of both. Sulphur removal using copper tailings has been trialed as a post- extraction cleanup to prevent reaction with the stainless steel extraction cells. Figure 4: Flow chart displaying the procedural steps used for OCL pesticides. Results Figure 5: Lindane mass spectra (insert: Lindane Calibration) Figure 6: 10ppb OCL mix standard in SIM mode. The Seine surface samples contain high quantities of sulphur and other co-eluting interference's, which means that cleanup with copper turnings and alumina alone are not sufficient. Next steps will examine an alumina:florisil mix cleanup. Figure 3: Dionex ASE 200 system. SOURCE: us/instruments/ins7387.html. Post extraction alumina cleanup Aluminium oxide was activated by muffling at 500  C and allowed to cool. 7%-deionised water was evenly distributed by mixing and left overnight to equilibrate. Glass wool was used as a bung in the columns, then 20g of activated alumina was tightly packed into the column using hexane and 2-3mm of anhydrous sodium sulphate was added to the top. Samples were evaporated to 1- 2ml and introduced to the column, then eluted through using hexane. GC/MS SIM Mode GC-MS and Large Volume Injection: The source = Electron Impact (EI); EM Voltage = ATUNE; Syringe volume = 25ul; Injector volume = 50ul (injected as 4 x 12.5ul); Injection mode = solvent vent; Injector programme = 50  C for 1 minute then 720  C/min to 300  C; PTV liner = multi-baffle, unpacked; Oven programme = 50(2) (0) (5.5) (Sandy, 2004). 50g (w/w) sample freeze-dried ASE OCLs were extracted from 20g (dry weight) sample under the following conditions: Oven temperature = 100  C; Pressure = 10 MPa (1500 psi); Oven Heat-up Time = 5 minutes; Static Time = 5 minutes; Flush Volume = 60% of extraction cell volume; Solvent = Hexane 2 extraction cycles of hexane In-cell alumina cleanup 20g of aluminium oxide (active basic) powder was put in the extraction cells, followed by a Whatman 30mm filter paper and then the sample. Each pair of extracts were combined and evaporated to 30ml using a TurboVap LV Evaporator. Post extraction sulphur cleanup 20g per sample of copper turnings were activated using a 5% nitric acid solution, rinsed with deionised water until a neutral pH was obtained, acetone rinsed, allowed to dry and added in small quantities to the samples until they no longer turned black. Microwave Assisted Solvent Extraction (MASE) - LCMS n for contemporary herbicide extraction and analysis. This study utilises a MARS 5 microwave with conditions based on a method developed by Shen and Lee, An extraction solvent of ultra pure water with 1% methanol is ramped to a temperature of 95°C over 5 minutes then this is held for 3 minutes, with 80% output (maximum power of 1200W) and a pressure of 200psi. A comparison of ultra pure water with 1% methanol and 100% methanol as extractants will be carried out to identify the most efficient. Preliminary results suggest that matrix effects are reducing extraction efficiency in the Medway sediment. Further steps will investigate this issue. Table 1: LC/MSn conditions


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