Tin and mercury and their speciation (organotin compounds and methylmercury) in worldwide red wine samples determined by ICP-MS and GC-ICP-MS.

One hundred and twenty-two red wines were analysed for their total tin, total mercury and speciation concentrations. Total Sn and Hg concentrations were in average 4.4 ± 7.2 µg/L and 0.22 ± 0.12 µg/L, respectively. Two GC-ICP-MS methods were developed and validated for speciation purposes: one to measure organotin compounds (OTCs) with internal standard correction; the other, to evaluate methylmercury (MeHg+) by isotopic dilution. Methyltins (mainly dimethyltin, but also monomethyltin) were the most abundant OTCs recovered. Methylation seems to occur biotically during the wine making process and not during the bottling time. Therefore, it also seems to be roughly dependent on the geographical origin of the wine. For higher OTCs, monobutyltin was the most regularly found, but dibutyltin and monooctyltin were also detected sometimes. MeHg+ was not recovered in any of the samples investigated, probably due to the low level of Hg. These results suggest that, in terms of these parameters, normal consumption of wine is not a hazard for human health.

Is it really organic?--multi-isotopic analysis as a tool to discriminate between organic and conventional plants.

Novel procedures for analytical authentication of organic plant products are urgently needed. Here we present the first study encompassing stable isotopes of hydrogen, carbon, nitrogen, oxygen, magnesium and sulphur as well as compound-specific nitrogen and oxygen isotope analysis of nitrate for discrimination of organically and conventionally grown plants. The study was based on wheat, barley, faba bean and potato produced in rigorously controlled long-term field trials comprising 144 experimental plots. Nitrogen isotope analysis revealed the use of animal manure, but was unable to discriminate between plants that were fertilised with synthetic nitrogen fertilisers or green manures from atmospheric nitrogen fixing legumes. This limitation was bypassed using oxygen isotope analysis of nitrate in potato tubers, while hydrogen isotope analysis allowed complete discrimination of organic and conventional wheat and barley grains. It is concluded, that multi-isotopic analysis has the potential to disclose fraudulent substitutions of organic with conventionally cultivated plants.

Speciation of antimony in injectable drugs used for leishmaniasis treatment (Glucantime®) by HPLC-ICP-MS and DPP.

Meglumine antimonate is the active of Glucantime® used for the treatment of leishmaniasis, a tropical disease caused by parasitic protozoa, and it is estimated that 12 million people worldwide are affected. This drug mainly contains Sb(V) under the form of an organic complex with N-methylglucamine (NMG). During the synthesis of this molecule, traces of Sb(III) may be present, also probably complexed. Due to the fact that Sb(III) is considered more toxic than Sb(V), it is important to evaluate the Sb(III) concentration in the drug samples. In the literature, very different concentrations for residual concentrations of Sb(III) in the drug ampoules are found. Therefore, to have a true insight of antimony speciation, two independent analytical methods were developed in this work. We used an anion exchange method coupled with inductively coupled plasma mass spectrometry (ICP-MS) which was cross-referenced with an electrochemistry method (differential pulse polarography (DPP)) that could be used for routine analysis on the production site. To obtain Sb species in detectable forms, the complexes between Sb species and NMG need to be broken. This was obtained by diluting samples in hydrochloric acid in deaerated conditions to avoid Sb redox reactions. For the two analytical methods, the HCl concentration was optimized to obtain simultaneously a complete destruction of the complexes as well as limited redox reactions for Sb(V) and Sb(III) released species. For high-performance liquid chromatography (HPLC)-ICP-MS, a dilution with 5 M HCl gives the better results. The side reaction is an oxidation of Sb(III) which can be limited by the removal of oxygen. When DPP is used, the major problem is the reduction of Sb(V) which is present in high amount in the samples. Working with 0.6 M HCl allows this problem to be minimized. When applied to different lots of Glucantime®, Sb(III) concentration values are in good agreement for the two analytical methods, with, for HPLC-ICP-MS, the advantage of the simultaneous detection of both Sb redox species.

Heavy metals and organochlorinated compounds in the European eel (Anguilla anguilla) from the Adour estuary and associated wetlands (France).

Heavy metals and organic pollutants were investigated in the Adour estuary (South West France) and associated wetlands using the European eel (Anguilla anguilla) as a bioindicator. Heavy metals (Cu, Cd, Zn, Pb, and Ag) were measured in soft tissue of yellow eels. Mercury (total Hg and MeHg) and organochlorinated compounds (7 PCBs, 11 OCPs) were analysed in muscle. Concentrations in muscle were in agreement with moderately contaminated environments in Europe and were below the norms fixed for eel consumption for heavy metals and OCPs. Analyses of liver showed a higher pressure of Ag and Zn in the downstream estuary than in the freshwater sites whereas Cd was lower in the estuary probably because of the salinity influence. According to quality classes 100% of eels from freshwater sites indicated clean or slightly polluted environments. However, total mercury concentrations were close to the thresholds fixed by the European Community in the downstream estuary, whereas the sum of PCBs was found to be greatly above the fixed value. 100% of the individuals from the estuary were classified in quality classes corresponding to polluted or highly polluted sites. These first results highlight the need of further investigations focused on mercury and PCBs in this area taking the seasonal temperature influence into account for a better understanding of the pollution distribution and the possible threat on the eel population from the Adour basin.

Simultaneous use of strontium:calcium and barium:calcium ratios in otoliths as markers of habitat: application to the European eel (Anguilla anguilla) in the Adour basin, South West France.

Sr:Ca and Ba:Ca ratios in water from the Adour estuary show a clear relationship with the salinity of the surrounding water for salinities <20, while ratios are almost constant above this level of salinity. A positive relationship was observed for the Sr:Ca ratio, whereas it was inverse for the Ba:Ca ratio. These two elemental ratios were measured in the otoliths of the European eels (Anguilla anguilla L.) using femtosecond laser ablation linked to an ICP-MS (fs-LA-ICP-MS). There was a direct relationship between the elemental ratios recorded in eel otoliths and those found in water from fresh and marine areas, suggesting that Sr:Ca and Ba:Ca ratios in eel otoliths can be used as markers of habitat in this estuary. Continuous profiling allowed the determination of three behaviour patterns in terms of habitat: freshwater, estuary and migratory individuals. Finally, the above results support the simultaneous use of both ratios for a better understanding of the migratory contingents and also as a relevant method to avoid a misidentification of environmental migratory history due to the presence of vaterite crystal in the otolith matrix.

Chromium speciation in solid matrices and regulation: a review.

In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials, workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different directives and recommendations and to critically review the currently existing standard methods and the methods published in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na(2)CO(3) solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence, the authors suggest an update of standard methods in the near future.

Mercury methylation by a microbial community from sediments of the Adour Estuary (Bay of Biscay, France).

In order to study the influence of microorganisms on the mercury biogeochemistry, the metal content and the structure of microbial communities were determined in sediments from stations along the Adour Estuary. The comparison of the bacterial communities and their distribution in function of the environmental parameters by Canonical Correspondence Analysis (CCA) revealed the influence of metals on the bacterial communities structure. Sediments where the bacterial communities are mostly influenced by methylmercury were incubated in slurries with or without mercury, under oxic and anoxic conditions. Methylmercury production was detected in the anoxic biotic slurries with a net methylation yield of 0.3% after 24 h. CCA based on T-RFLP profiles revealed the impact of mercury addition on the bacterial communities structure. In addition, 17 bacterial strains, mainly sulphate-reducing bacteria involved in mercury methylation, were isolated and identified.

Development of analytical procedures for the determination of hexavalent chromium in corrosion prevention coatings used in the automotive industry.

The European directive 2000/53/EC limits the use of Cr(VI) in vehicle manufacturing. Although a maximum of 2 g of Cr(VI) was authorised per vehicle for corrosion prevention coatings of key components, since July 2007 its use has been prohibited except for some particular applications. Therefore, the objective of this work was to develop direct analytical procedures for Cr(VI) determination in the different steel coatings used for screws. Instead of working directly with screws, the optimisation of the procedures was carried out with metallic plates homogeneously coated to improve the data comparability. Extraction of Cr(VI) from the metallic parts was performed by sonication. Two extraction solutions were tested: a direct water extraction solution used in standard protocols and an ammonium/ammonia buffer solution at pH 8.9. The extracts were further analysed for Cr speciation by high-performance liquid chromatography (HPLC) inductively coupled plasma (ICP) atomic emission spectrometry or HPLC ICP mass spectrometry depending on the concentration level. When possible, the coatings were also directly analysed by solid speciation techniques (X-ray photoelectron spectroscopy, XPS, and X-ray absorption near-edge structure, XANES) for validation of the results. Very good results between the different analytical approaches were obtained for the sample of coating made up of a heated paint containing Zn, Al and Cr when using the extracting buffer solution at pH 8.9. After a repeated four-step extraction procedure on the same portion test, taking into account the depth of the surface layer reached, good agreement with XPS and XANES results was obtained. In contrast, for the coatings composed of an alkaline Zn layer where Cr(VI) and Cr(III) are deposited, only the extraction procedure using water allowed the detection of Cr(VI). To elucidate the Cr(VI) reduction during extraction at pH 8.9, the reactivity of Cr(VI) towards different species of Zn generally present in the coatings (metallic Zn and zinc oxide) was studied. The results showed that metallic Zn rapidly reduces Cr(VI), whereas this reaction is less evident in the presence of zinc oxide. Water was then retained for coatings containing metallic Zn.

High-frequency archives of manganese inputs to coastal waters (Bay of Seine, France) resolved by the LA-ICP-MS analysis of calcitic growth layers along scallop shells (Pecten maximus).

During their growth, bivalves are recognized to archive minor and trace elements within their shells which may reflect environmental conditions at the sediment-water interface (SWI). Shells from juvenile Great Scallops (Pecten maximus (L.)), which develop a daily calcite growth layer, were collected in the Bay of Seine (France) and examined by matrix-matched LaserAblation ICP-MS analysis for Mn concentrations along their growth period, from April to October (year 2004). The backdated Mn concentration profiles were compared with environmental variables (e.g., temperature, salinity, chlorophyll a, oxygen, etc.) measured continuously at monitoring stations in riverine, estuarine, and coastal waters. The objective was first to perform microanalyses of Mn composition along the shell reflecting episodic enrichment or depletion in such environment, and second, to depict Mn cycling and inputs at the SWI according to the measured profiles. Basically, Mn concentration profiles mostly depend on established estuarine and coastal biogeochemical processes that lead to an increase of dissolved Mn concentration available for shell uptake. Potential particulate Mn fluxes from the Seine River, that control both particulate and dissolved Mn input to the bay, are strongly correlated with shell Mn concentrations from April to July (?r = 0.95, n = 8, p < 0.05). In late summer, riverine inputs can not only provide an explanation for the shell Mn enrichments which suggest additional sources of Mn. During this period, two other processes also contribute to the release of dissolved Mn in coastal waters and the increase of shell Mn content: (1) successive redox oscillations within the high turbidity zone of the macrotidal Seine estuary and (2) postbloom reductive conditions developed at the SWI of the Seine Bay under periodic seasonal eutrophication. This study demonstrates that incremental Mn concentrations profiles in scallop shells are a relevant natural archive to evaluate the processes governing Mn inputs into coastal environments at a daily scale.

Multi-isotopic determination of plutonium (239Pu, 240Pu, 241Pu and 242Pu) in marine sediments using sector-field inductively coupled plasma mass spectrometry.

Among the transuranic elements present in the environment, plutonium isotopes are mainly attached to particles, and therefore they present a great interest for the study and modelling of particle transport in the marine environment. Except in the close vicinity of industrial sources, plutonium concentration in marine sediments is very low (from 10(-4) ng kg(-1) for (241)Pu to 10 ng kg(-1) for (239)Pu), and therefore the measurement of (238)Pu, (239)Pu, (240)Pu, (241)Pu and (242)Pu in sediments at such concentration level requires the use of very sensitive techniques. Moreover, sediment matrix contains huge amounts of mineral species, uranium and organic substances that must be removed before the determination of plutonium isotopes. Hence, an efficient sample preparation step is necessary prior to analysis. Within this work, a chemical procedure for the extraction, purification and pre-concentration of plutonium from marine sediments prior to sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) analysis has been optimized. The analytical method developed yields a pre-concentrated solution of plutonium from which (238)U and (241)Am have been removed, and which is suitable for the direct and simultaneous measurement of (239)Pu, (240)Pu, (241)Pu and (242)Pu by SF-ICP-MS.

Matrix-matched quantitative analysis of trace-elements in calcium carbonate shells by laser-ablation ICP-MS: application to the determination of daily scale profiles in scallop shell (Pecten maximus).

A micro-scale method has been developed for analysis of trace-element concentration profiles in the calcium carbonate shell of the Great Scallop (Pecten maximus). UV laser ablation at 266-nm coupled with ICP-MS detection was used to analyse daily calcite striae of shell samples to obtain high temporal resolution of trace element incorporation. Analysis of scallop shells was carefully examined to determine the quality of calcium carbonate ablation and calibration. An accurate external calibration method based on matrix matching was developed. Twelve sodium-free enriched calcium carbonate standards containing up to twenty-four elements were prepared, by co-precipitation with aqueous ammonia and NH(4)HCO(3), and subsequently back-calibrated in the laboratory. These CaCO(3) standards were found to be homogenous and their use enabled sensitive quantitative analysis (detection limits of a few ng g(-1)) over a wide range of concentrations (0.1 to 500 microg g(-1)). Use of these CaCO(3) standards was also evaluated by analysis of three calcium-rich certified reference materials. Because calibration was consistent with the certified results, this analytical method is a sensitive tool for analysis of environmental calcium carbonate matrices. Repeated analysis of scallop shell samples collected simultaneously at the same location showed that the trace elements are homogeneously distributed along a stria. The reliability of such in-situ records of biogenic calcium carbonate (scallop shells) is apparent from the inter-individual and inter-annual reproducibility of the trace element profiles.

Certification of methylmercury content in two fresh-frozen reference materials: SRM 1947 Lake Michigan fish tissue and SRM 1974b organics in mussel tissue (Mytilus edulis).

This paper describes the development of two independent analytical methods for the extraction and quantification of methylmercury from marine biota. The procedures involve microwave extraction, followed by derivatization and either headspace solid-phase microextraction (SPME) with a polydimethylsiloxane (PDMS)-coated silica fiber or back-extraction into iso-octane. The identification and quantification of the extracted compounds is carried out by capillary gas chromatography/mass spectrometric (GC/MS) and inductively coupled plasma mass spectrometric (GC/ICP-MS) detection. Both methods were validated for the determination of methylmercury (MeHg) concentrations in a variety of biological standard reference materials (SRMs) including fresh-frozen tissue homogenates of SRM 1946 Lake Superior fish tissue and SRM 1974a organics in mussel tissue (Mytilus edulis) and then applied to the certification effort of SRM 1947 Lake Michigan fish tissue and SRM 1974b organics in mussel tissue (Mytilus edulis). While past certifications of methylmercury in tissue SRMs have been based on two independent methods from the National Institute of Standards and Technology (NIST) and participating laboratories, the methods described within provide improved protocols and will allow future certification efforts to be based on at least two independent analytical methods within NIST.

Multielemental speciation of trace elements in estuarine waters with automated on-site UV photolysis and resin chelation coupled to inductively coupled plasma mass spectrometry.

An integrated approach for the accurate determination of total, labile and organically bound dissolved trace metal concentration in the field is presented. Two independent automated platforms consisting of an ultraviolet (UV) on-line unit and a chelation/preconcentration/matrix elimination module were specifically developed to process samples on-site to avoid sample storage prior to inductively coupled plasma mass spectrometry (ICP-MS) analysis. The speciation scheme allowed simultaneous discrimination between labile and organic stable dissolved species of seven trace elements including Cd, Cu, Mn, Ni, Pb, U and Zn, using only 5ml of sample with detection limits ranging between 0.6ngl(-1) for Cd and 33ngl(-1) for Ni. The influence of UV photolysis on organic matter and its associated metal complexes was investigated by fluorescence spectroscopy and validated against natural samples spiked with humic substances standards. The chelation/preconcentration/matrix elimination procedure was validated against an artificial seawater spiked sample and two certified reference materials (SLRS-4 and CASS-4) to ensure homogenous performance across freshwater, estuarine and seawater samples. The speciation scheme was applied to two natural freshwater and seawater samples collected in the Adour Estuary (Southwestern, France) and processed in the field. The results indicated that the organic complexation levels were high and unchanged for Cu in both samples, whereas different signatures were observed for Cd, Mn, Ni, Pb, U and Zn, suggesting organic ligands of different origin and/or their transformation/alteration along estuarine water mixing.

Evaluation of analytical strategies for the determination of metal concentrations to assess landfill leachate contamination.

Due to the complex nature of landfill leachates, metal and metalloid analyses prove to be tricky and suffer from a lack of standard protocols. A complete approach has been adopted to investigate the influence of the different steps during the sample processing of French landfill leachates. The validation of the entire protocol has been achieved using a laboratory reference material. This material, which is a real landfill leachate, is representative of real samples. Its evaluation has allowed a quality control for metal and metalloid analyses in landfill leachates. Precautions concerning storage temperature, aeration and filtration are proposed to perform accurate metal analyses in these complex matrices. The sample processing has been applied to the seasonal monitoring of a French landfill. The assessment of major leachate metallic contaminants such as As, Cr, Sb, Sn, has been performed by evaluating the relative enrichment of metals and metalloids in comparison with rain water and groundwater. In addition, hydrological data are useful and complementary information for pointing out the main factors affecting metal concentrations and thus their potential remobilisation pathways.

Improvement of analytical performances for mercury speciation by on-line derivatization, cryofocussing and atomic fluorescence spectrometry.

A modified automated on-line hyphenated system for simultaneous inorganic ionic mercury (Hg(2+)) and monomethylmercury (MeHg(+)) analysis by hydride generation (HG) or ethylation (Eth), cryofocussing, gas chromatography (GC) separation and atomic fluorescence spectrometry (AFS) detection has been improved. Both derivatization methods are investigated with respect to the chromatographic and analytical performances. They can be both affected by interferences when the AFS detection system is used. Water vapor removal using a soda lime moisture trap improves significantly the chromatographic performances, the reproducibility and the detection limits for Hg(2+) and MeHg(+) analyzed with both methods. For ethylation (Eth) derivatization, a scattering interference generated from low-quality ethylation reagent has also been eliminated. For HG, improved detection limits are 0.13ngl(-1) and 0.01ngl(-1) for Hg(2+) and MeHg(+), respectively (0.1l water sample), and reproducibility are 5% for Hg(2+) (20ngl(-1)) and MeHg(+) (5ngl(-1)). Improved detection limits for Eth are 0.22ngg(-1) for Hg(2+) and 0.02ngg(-1) for MeHg(+) (1g dry sediment sample) and the reproducibility are 5-6% for Hg(2+) and MeHg(+) (1-2ngg(-1)).

Simultaneous sample preparation and species-specific isotope dilution mass spectrometry analysis of monomethylmercury and tributyltin in a certified oyster tissue.

A rapid, accurate, sensitive, and simple method for simultaneous speciation analysis of mercury and tin in biological samples has been developed. Integrated simultaneous sample preparation for tin and mercury species includes open focused microwave extraction and derivatization via ethylation. Capillary gas chromatography-inductively plasma mass spectrometry (CGC-ICPMS) conditions and parameters affecting the analytical performance were carefully optimized both for species-specific isotope dilution analysis of MMHg and TBT and for conventional analysis of MBT and DBT201Hg-enriched monomethylmercury and 117Sn-enriched tributyltin were used for species-specific isotope dilution mass spectrometry (SIDMS) analysis. As important, accurate isotope dilution analysis requires equilibration between the spike and the analyte to achieve successful analytical procedures. Since the spike stabilization and solubilization are the most critical and time-consuming steps in isotope dilution analysis, different spiking procedures were tested. Simultaneous microwave-assisted spike stabilization and solubilization can be achieved within less than 5 min. This study originally introduces a method for the simultaneous speciation and isotope dilution of mercury and tin in biological tissues. The sample throughput of the procedure was drastically reduced by fastening sample preparation and GC separation steps. The accuracy of the method was tested by both external calibration analysis and species-specific isotope dilution analysis using the first biological reference material certified for multielemental speciation (oyster tissue, CRM 710, IRMM). The results obtained demonstrate that isotope dilution analysis is a powerful method allowing the simultaneous speciation of TBT and MMHg with high precision and excellent accuracy. Analytical problems related to low recovery during sample preparation are thus minimized by SIDMS. In addition, a rapid procedure allows us to establish a performant routine method using CGC-ICPMS technique.

Using speciated isotope dilution with GC-inductively coupled plasma MS to determine and unravel the artificial formation of monomethylmercury in certified reference sediments.

Speciated isotope-dilution mass spectrometry (SID-MS) is claimed to be an absolute method; however, it has been found to be affected by artifact monomethylmercury (MMHg) formation in sediments. The determination of MMHg in sediments was carried out by SID-MS after open-focused microwave extraction. The extracted mercury species were then ethylated and separated by capillary gas chromatography (CGC). Isotope ratios (peak area ratios at different masses) were measured by on-line ICP-MS detection of the CGC-separated compounds. Reproducibility of 202Hg/201Hg isotope ratio measurements were 0.60% for MeEtHg and 0.69% for Et2Hg; for 202Hg/199Hg, 0.43 and 0.46%, respectively, were determined. The absolute detection limits for CGC-ICPMS measurements were better than 26 fg for 202Hg, 20 fg for 201Hg, and 24 fg for 199Hg. For the direct determination of MMHg in sediment reference materials (CRM 580, IAEA 356, and IAEA 405), higher values than the certified were always found. Systematic experiments were carried out to localize the sources of the unintentional abiotic methylmercury formation during analysis. Different spiking and derivatization procedures (either ethylation, propylation, or derivatization by Grignard reagents) were tested. In addition, isotopically enriched inorganic mercury was spiked. The amount of inorganic mercury initially present in the sample was found to be the critical factor that should be known and carefully controlled. A simple solvent extraction technique involving no critical cleanup steps was applied in order to reduce high Hg2+ amounts. The method was applied to the determination of MMHg in sediment reference material IAEA-405 with satisfactory results after organic solvent extraction. The limitations of applicability of the proposed method are evaluated as related to inorganic mercury, organic carbon, and sulfur contents. The results obtained confirmed that available sediment reference materials are adequate to achieve traceable mercury speciation analysis and to detect potential sources of MMHg artifact formation.

Development of analytical procedures for determination of total chromium by quadrupole ICP-MS and high-resolution ICP-MS, and hexavalent chromium by HPLC-ICP-MS, in different materials used in the automotive industry.

A European directive was recently adopted limiting the use of hazardous substances such as Pb, Hg, Cd, and Cr(VI) in vehicle manufacturing. From July 2003 a maximum of 2 g Cr(VI) will be authorised per vehicle in corrosion-preventing coatings of key components. As no standardised procedures are available to check if produced vehicles are in agreement with this directive, the objective of this work was to develop analytical procedures for total chromium and Cr(VI) determination in these materials. The first step of this study was to optimise digestion procedures for total chromium determination in plastic and metallic materials by inductively coupled plasma mass spectrometry (ICP-MS). High resolution (HR) ICP-MS was used to examine the influence of polyatomic interferences on the detection of the (52)Cr(+) and (53)Cr(+) isotopes. If there was strong interference with m/ z 52 for plastic materials, it was possible to use quadrupole ICP-MS for m/ z 53 if digestions were performed with HNO(3)+H(2)O(2). This mixture was also necessary for digestion of chromium from metallic materials. Extraction procedures in alkaline medium (NH(4)(+)/NH(3) buffer solution at pH 8.9) assisted by sonication were developed for determining Cr(VI) in four different corrosion-preventing coatings by HPLC-ICP-MS. After optimisation and validation with the only solid reference material certified for its Cr(VI) content (BCR 545; welding dusts), the efficiency of this extraction procedure for screw coatings was compared with that described in the EN ISO 3613 standard generally used in routine laboratories. For coatings comprising zinc and aluminium passivated in depth with chromium oxides the extraction procedure developed herein enabled determination of higher Cr(VI) concentrations. This was also observed for the screw covered with a chromium passivant layer on zinc-nickel. For coating comprising a chromium passivant layer on alkaline zinc the standardized extraction procedure was more efficient. In the case of painted metallic plate, because of a reactive matrix towards Cr(VI), its extraction without degradation was difficult to perform.

Determination of tributyltin in marine sediment: Comité Consultatif pour la Quantité de Matière (CCQM) pilot study P-18 international intercomparison.

The capabilities of National Metrology Institutes (NMIs-those which are members of the Comité Consultatif pour la Quantité de Matière (CCQM)of the CIPM) and selected outside "expert" laboratories to quantitate (C(4)H(9))(3)Sn(+) (TBT) in a prepared marine sediment were assessed. This exercise was sanctioned by the 7th CCQM meeting, April 4-6, 2001, as an activity of the Inorganic Analysis Working Group and was jointly piloted by the Institute for National Measurement Standards of the National Research Council of Canada (NRC) and the Laboratory of the Government Chemist (LGC), UK. A total of 11 laboratories submitted results (7 NMIs, and 4 external labs). Two external laboratories utilized a standard calibration approach based on a natural abundance TBT standard, whereas all NMIs relied upon isotope dilution mass spectrometry for quantitation. For this purpose, a species specific (117)Sn-enriched TBT standard was supplied by the LGC. No sample preparation methodology was prescribed by the piloting laboratories and, by consequence, a variety of approaches was adopted by the participants, including mechanical shaking, sonication, accelerated solvent extraction, microwave assisted extraction and heating in combination with Grignard derivatization, ethylation and direct sampling. Detection techniques included ICP-MS (with GC and HPLC sample introduction), GC-MS, GC-AED and GC-FPD. Recovery of TBT from a control standard (NRCC CRM PACS-2 marine sediment) averaged 93.5+/-2.4% ( n=14). Results for the pilot material averaged 0.680+/-0.015 micro mol kg(-1) ( n=14; 80.7+/-1.8 micro g kg(-1)) with a median value of 0.676 micro mol kg(-1). Overall, performance was substantially better than state-of-the-art expectations and the satisfactory agreement amongst participants permitted scheduling of a follow-up Key comparison for TBT (K-28), a Pilot intercomparison for DBT (P-43), and certification of the test sediment for TBT content and its release as a new Certified Reference Material (HIPA-1) with a TBT content of 0.679+/-0.089 micro mol kg(-1) (expanded uncertainty, k=2, as Sn) (80.5+/-10.6 micro g kg(-1)).

Mercury speciation in sediments of a tropical coastal environment.

The speciation of mercury in tropical coastal areas, although scarcely studied, has presented an odd behaviour when compared with the results obtained in temperate environments. In this work, we measured the concentrations of mercury species (mercuric mercury, methyl-mercury and dimethyl-mercury) in the sediments of Sepetiba Bay (Brazil) and compared these with geochemical parameters. Twenty-eight sediment samples were extracted in an open microwave system and mercury speciation was carried out by ethylation, cryogenic focusing, gas chromatography and quartz furnace atomic absorption spectrometry. Fraction < 63 microm, organic carbon and total sulphur contents and redox potential were measured in order to outline the geochemical characteristics of the sediments. While mercuric mercury presented concentrations ranging between 22.65 and 134.61 ng g(-1), methyl-mercury concentrations ranged between < 2.0 and 4.4 ng g(-1). Only a few dimethyl-mercury concentrations were relatively high (up to 14.6 ng g(-1)). The results of mercuric mercury presented an unexpected positive correlation with sulphur contents showing that mercury is forming stable sulphide complexes, even under very reducing conditions. This would render mercury available for t he formation of methyl- or dimethyl-mercury that would be both fixed in the sediments and volatilised.