Sediment Reference Materials

The project was coordinated by the Studio di Ingegneria Ambientale (Milano, Italy). The preparation of the sediment reference material was carried out by Ecoconsult (Gavirate, Italy) and the Environment Institute of the EC Joint Research Centre of Ispra (Italy). The homogeneity and stability were verified at two laboratories from the Presidio Multizonale di Prevenzione (La Spezia and Venice, Italy). The material characterization (with regard to bacterial flora) was performed at the University of Siena (Italy). 

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Results. Various solvent mixtures were tested for extraction efficiency. The test sample was a bone-dry sediment reference material containing 24.6 ppm of Arochlor 1242. This reference material is a real sediment from New Bedford Harbor which was homogenized and carefully assayed for PCB s by the Cincinnati EPA facility. Figure 3 shows recovery of 1242 using (1) hexane alone, (2) hexane and water (1 1), (3) hexane, water, and ethyl ether, (4) ethyl ether and water, (5) ethyl ether, water, and methanol, (6) methanol and hexane (1 1), and (7) water, methanol, and hexane (1 4 5). This last combination appears to give the best recovery. When added in this order to a dry sample, the effect of the water is to wet the sample, thus permitting extraction by methanol. The extracted PCB is partitioned almost exclusively into the hexane from the aqueous methanol. Final recovery is calculated from initial weight and hexane volume. 

Figure 3. Recovery of Arochlor 1242 from a sediment reference material using different solvents.

Figure 4. Recovery efficiency of Arochlor 1242 from sediment reference material.

Lee H-B and Chau ASY (1987) Analytical reference materials Part VII. development and certification of a sediment reference material for total polychlorinated biphenyls. Analyst 112 37-40. Meinke WW (1971) Standard reference materials for clinical measurements. Anal Chem 43(6) 28A-47A. 

Bowman WS (1994) Stream sediment reference materials STSD-i to STSD-4. In Catalogue of Certified Reference Materials, CCRMP 94-iE. Natural Resources Canada, Ottawa. 

Schantz mm, Benner BA Jr, Chesler SN, Koster BJ, Hbhn KE, Stone SF, Kelly WR, Zeisler R, Wise SA (1990) Preparation and analysis of a marine sediment reference material for the determination of trace organic constituents. Fresenius J Anal Chem 338 501-514. 

Horvat M, Mandic V, Liang L, Bloom NS, Padberg S, Lee Y.-H, Hintelmann H, and Benoit J (1994) Certification of methylmercury compounds concentration in marine sediment reference material, IAEA-356. Appl Organomet Chem 8 533-540. 

Wise SA, Schantz MM, Benner BA Jr, Hays M J, and Schiller SB (1995) Certification of polycyclic aromatic hydrocarbons in a marine sediment reference material. Anal Chem 67 1171-1178. 

Comment A certified marine sediment reference material mentioned (NIST, NRCC ) But no other details given on the CRM used. 

Hammerschmidt and Fitzgerald [ 127] have studied the formation of artifact methylmercury during extraction from a sediment reference material. 

Lee and Chau [66] have discussed the development and certification of a sediment reference material for total polychlorobiphenyls. Alford Stevens et al. [49] in an inter-laboratory study on the determination of polychlorobiphenyls in environmentally contaminated sediments showed the mean relative standard deviation of measured polychlorobiphenyl concentrations was 34%, despite efforts to eliminate procedural variations. Eganhouse and Gosset [67] have discussed the sources and magnitude of bias associated with the determination of polychlorobiphenyls in environmental sediments. Heilman [30] studied the adsorption and desorption of polychlorobiphenyl on sediments. 

Sediment reference materials should be developed for both open-ocean and coastal areas. Open-ocean sediments should include carbonate-rich, silicate-rich, and clay mineral-rich types. Coastal sediments should be of the same types and should include a deltaic sediment that has not been in contact with seawater. Taken together with the algal-based materials, these sediment materials would represent a wide range of diagenetic states. The committee recommends that each of these solid... 

Reference materials that represent the primary deep-sea and coastal depositional environments and biological materials would solve many of the problems that radiochemists face in analysis of sediments from these settings. Radiochemists require reference materials comprising the primary end member sediment and biological types (calcium carbonate, opal, and red clay from the deep-sea and carbonate-rich, silicate-rich, and clay mineral-rich sediments from coastal environments and representative biological materials). Additional sediment reference material from a river delta would be valuable to test the release of radionuclides that occurs as riverine particles contact seawater. 

All of these sediment reference materials would provide stable homogeneous materials containing a wide variety of chemical constituents that could be studied at the discretion of the ocean sciences community, and may ultimately be assigned consensus values for a number of important additional organic and inorganic analytes. 

Several organizations (e.g., NIST, NRC-Canada, and IAEA) provide sediment reference materials containing radionuclides, many of which are only certified for artificial radionuclides ( Cs, Sr, Am, and Pu). Certain specific radionuclides have no certified natural matrix materials, including ocean, lake, and river sediments. Although these sediments are certified for a few naturally occurring and artificial radionuclides, the extent of radioactive equilibrium of the uranium and thorium decay series in these environmental materials is not provided. NIST currently offers an ocean sediment Standard Reference Material (SRM 4357) in... 

Quevauviller, Ph., Rauret, G., L6pez-Sanchez, J.-F., Rubio, R., Ure, A. and Muntau, H. (1997d) Certification of trace metal extractable contents in a sediment reference material (CRM 601) following a three-step sequential extraction procedure. Sci. Total Environ., 205, 223. 

A modified BCR sequential extraction was recommended based on this work, and its performance compared with the original BCR procedure via an interlaboratory trial (Rauret et al, 1999). Improved reproducibility was obtained. A new sediment reference material CRM 701 has been certified for metals extractable by the modified BCR procedure (Pueyo et al., 2001). The modified extraction protocol is given in the Appendix. It is important to emphasise that extractions should be performed exacdy as described if results comparable with other users are to be obtained. 

A complementary project has started in 1997 by an interlaboratory study on butyl-and phenyl-tin compounds in a freshwater sediment reference material. A certification campaign has been conducted in 1998 and the certification of the six compounds (mono-, di- and tri-butyl and phenyltins) is promising [15]. All precautions have been taken to ensure the material stability (storage at -20°C). 

A three step extraction procedure was designed based on acetic acid extraction (step 1), hydroxylammonium chloride extraction (step 2) and hydrogen peroxide/ammonium acetate extraction (step 3). This scheme (described elsewhere [22]) was tested in two interlaboratory trials on Cd, Cr, Cu, Ni, Pb and Zn on freshwater sediment reference materials [23,24], the results of which are summarised in Table 9.6. 

Perez, S. and Barcelo, D., Evaluation of antipyrene and antifluorene immunosorbent clean up for PAHs from sludge and sediment reference materials followed by liquid chromatography and diode... 

The reliability was tested by analyzing a certified marine sediment reference material CRM 462. The TBT and DBT concentrations found were in good agreement with the certified values. The MBT concentration was not certified in that sediment. 

Specific chapters then focus on different projects on speciation analysis. Chapter 4 deals with interlaboratory studies on methylmercury in fish and sediment Chapter 5 describes the collaborative projects to certify organotins in sediment RMs and mussel tissues Chapter 6 gives an overview of the certification project on trimethyllead in simulated rainwater and urban dust Chapter 7 describes the certification project on arsenic species in fish tissues Chapter 8 focuses on the intercomparison and tentative certification of Se(IV) and Se(VI) in simulated freshwater Chapter 9 deals with a feasibility study to stabilize Cr species in solution followed by the certification of Cr(III) and Cr(VI) in lyophilized solutions and welding dust Chapter 10 gives a review of methods used for A1 speciation Chapter 11 develops the overall collaborative project to standardize single and sequential extraction procedures for soil and sediment analysis, followed by interlaboratory studies and certification of soil and sediment reference materials. 

The main difficulty in preparing a sediment reference material for interlaboratory studies on chemical species is to achieve the stability of the relevant compounds [12]. With respect to methylmercury, the main source of instability is due to bacteria, either by demethylation [88,89] or formation of volatile dimethylmercury [90]. The conversion is indirectly provoked by the biological activity of various types of bacteria, such as (i) aerobic mesophilic heterotrophic microorganisms, (ii) anaerobic sulfate-reducing bacteria and (iii) anaerobic spore-forming bacteria. In order to control the remaining bacteria present after different irradiation treatments, a bacterial enumeration was performed on samples which were dehydrated after homogenization and irradiated at various 7-ray doses (0, 4, 8, 12, 25 and 50 kGy). The determination of the sulfate-... 

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