A pilot study for the production of a certified reference material for trace elements in honey

In the context of the general mandate of the European Union Community Reference Laboratory (CRL) for residues in living animals and their products established at the Istituto Superiore di Sanità, a pilot study was undertaken to assess the possibility of producing a new certified reference material (CRM) for trace elements in a matrix of honey. The elements considered were As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sn, V and Zn. Their determination was performed by inductively coupled plasma (ICP)-based techniques. Data obtained with different ICP techniques were generally in good agreement. In light of these results, the next step was the effective production of a candidate CRM in a honey matrix. In the preliminary phase, two different types of honey, i.e., Eucalyptus (solid and sticky) and Robinia (viscous and sticky), were pretreated at the Institute for Reference Materials and Measurements, Joint Research Centre, European Commission (EC-JRC-IRMM) in order to produce the materials candidate for the certification process. Approximately 600 ampoules were thus produced for the Robinia honey and 450 ampoules for the Eucalyptus honey, each ampoule containing 5 g of an aqueous solution of honey (with 20% and 30% high purity water, respectively) and sealed under inert gas (Ar). A ring test to determine the levels of the chemical elements and a long-term study to evaluate the stability of the samples is in progress. Tentative figures for the analytes of interest are (in ng g⁻¹): Robinia, As, 1.28±0.09; Cd, 0.59±0.08; Cr, 2.36±0.21; Cu, 57.6±3.2; Fe, 209±9; Mn, 90.8±3; Ni, 18.1±0.6; Pb, 23±1.5; Sn, 8.10±0.35; V, 1.19±0.37; and Zn, 178±4; Eucalyptus, As, 3.18±0.21; Cd, 0.70±0.08; Cr, 2.73±0.22; Cu, 141±6; Fe, 926±16; Mn, 1905±81; Ni, 7.77±0.4; Pb, 138±4; Sn, 7.97±0.16; V, 3.47±0.15; and Zn, 405±9.     

Development of new reference materials for the determination of cadmium,chromium, mercury and lead in polycarbonate

Reference materials for quantitative determination of Cd, Cr, Hg and Pb in polycarbonate were developed. Reference materials with two concentration level of elements were prepared by adding appropriate amounts of chemicals to a blank polycarbonate base material. It was shown that ten bottles with triplicate analysis are enough to demonstrate the homogeneity of these candidate reference materials. The statistical results also showed no significant trends in both short-term stability test for four weeks and long-term stability test for twelve months. The certification of the four elements was carried out by isotope-dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) with microwave-assisted digestion. Certification of candidate reference materials in a single laboratory was confirmed with interlaboratory comparison participated by a certain number of well-recognized testing laboratories in Korea. The certified values and expanded uncertainties (k = 2) for the candidate reference material with low level and the one with high level were (51.7 ± 2.1) mg kg⁻¹ Cd, (103.8 ± 2.9) mg kg⁻¹ Cd, (98.8 ± 4.5) mg kg⁻¹ Cr, (1004 ± 49.8) mg kg⁻¹ Cr, (107.4 ± 4.6) mg kg⁻¹ Hg, (1133 ± 50.7) mg kg⁻¹ Hg, (94.8 ± 3.7) mg kg⁻¹ Pb and (988.4 ± 53.6) mg kg⁻¹ Pb, respectively. The reference materials developed in this study demonstrated their suitability for the quality assurance in Cd, Cr, Hg and Pb analysis for the implementation of RoHS Directive.     

A pilot study on the contents of selected pollutants in fish from the Tiber River (Rome)

In the framework of a project aimed at the study of the catchment basin of the Tiber River (Latium Region, Italy), a pilot survey was conducted in order to assess the presence of selected toxic trace elements, namely As, Cd, Hg and Pb, in muscle tissues of fish caught in different tracts of Tiber River (urban area of Rome and different rural areas upstream and downstream). The analysed species were Leuciscus cephalus (Ciprinidae) and Anguilla anguilla (Anguillidae). Determinations were carried out by means of Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS). Preliminary data (ranges of concentration in μg g⁻¹, freeze-dried mass: As, 0.73–3.62; Cd, 0.0002–0.001; Hg, 0.18–0.31; Pb, 0.02–0.09) revealed no significant differences among the sets of results relevant to the various sampling stations. The total content of each element seems to be related with a general condition of low-level pollution of the area under study.     

A pilot study for the preparation of a new Reference Material based on antarctic krill

The preparation of new Certified Reference Materials (CRMs) of antarctic matrices forms the backbone of an ongoing project in the framework of the Italian National Program for Antarctic Research. The first CRM of this kind (MURST-ISS-A1 Antarctic Marine Sediment) is already available. The second phase focuses on the certification of antarctic krill, a small shrimp extremely abundant in the Southern Ocean. The total mass of krill available for this purpose is approximately 44 kg and results from the combination of three different catches (Ross Sea, Marguerite Bay and Livingston Island, respectively). The quantification of the following elements in the raw mass appears to be affordable by current analytical techniques, values being in the range of (in μg/g) 0.11–0.30 for As, 0.03–0.12 for Cd, 0.06–0.23 for Cr, 6.1–21 for Cu, 5.7–7.6 for Fe, 0.005–0.008 for Hg, 0.7–1.2 for Mn, 0.013– 0.077 for Ni, 0.04–0.57 for Pb and 12–16 for Zn. On the other hand, the average values ascertained in freeze-dried krill are as a rule one order of magnitude higher, i.e., (in μg/g), 3.2 for As, 0.6 for Cd, 1.8 for Cr, 75 for Cu, 61 for Fe, 0.025 for Hg, 4.6 for Mn, 0.7 for Ni, 2.1 for Pb and 81 for Zn. Information on the pretreatment of krill and details on the planned certification campaign are also given. Received: 10 June 1997 / Revised: 24 September 1997 / Accepted: 28 September 1997     

Establishment of SI-traceable reference values for the content of various elements in the IMEP-14 sediment sample

For the first time in the International Measurement Evaluation Programme (IMEP)-14, a sediment sample was offered to analytical laboratories to perform measurements of As, Cd, Cr, Cu, Fe, Pb, Hg, Ni, U and Zn. In line with IMEP policy, the results were presented according to the certified / assigned reference values established by several reference laboratories around the world. The certification campaign is described in detail. Isotope dilution mass spectrometry was applied as a primary method of measurement, whenever possible, to achieve SI-traceable results. For reference measurements of As, Fe, Hg and Zn, k₀-neutron activation analysis and Zeeman atomic absorption spectrometry were applied. The reference values (ranges) were characterised as ”certified” (for Cd, Cr, Pb, Ni and U) or ”assigned” (for As, Cu, Fe, Hg and Zn) according to IMEP policy. The measurement uncertainty of the certified / assured reference values was calculated according to the ISO/BIPM Guide. Received: 7 June 2001-10-27 Accepted: 19 August 2001     

Certification of reference materials for Cd, Cr, Hg and Pb in polypropylene

Two reference materials, at relatively low and high concentrations (GBW08404 and GBW08405), for analysis of the mass fractions of Cd, Cr, Hg and Pb in polypropylene were developed. The reference materials were prepared by doping blank polypropylene base material with Cd, Cr, Hg and Pb in the form of oxides, salts or pigments. Homogeneity and stability studies were performed by inductively coupled plasma mass spectrometry. The certification of the four analytes was carried out by isotope-dilution mass spectrometry (IDMS) with microwave-assisted digestion. Combined uncertainties were calculated from the IDMS uncertainty evaluation budget and the uncertainty of the homogeneity. The mass fractions of Cd, Cr, Hg and Pb of the two certified reference materials (CRMs) were from 8 to 1,000 mg kg⁻¹. The two samples were also used in an interlaboratory comparison scheme in which National Institute of Metrology, China, National Metrological Institute of Japan and Korea Research Institute of Standards and Science participated. The agreement of the comparison results proved that the certification procedure of the CRMs is valid and that the certified values of Cd, Cr, Hg and Pb are accurate and reliable.     

A CRL–IRMM joint proficiency test for trace elements in fish tissue

The Community Reference Laboratory (CRL) for residues and contaminants in food of animal origin at the Istituto Superiore di Sanità (ISS) plans and undertakes on a regular basis Proficiency Tests Schemes (PTSs) focused on the residues under its responsibility, as prescribed by the Council Directive 96/23/EC of April 29, 1996. In consideration of the benefits ensuing from a constant monitoring of the daily activities of the National Reference Laboratories (NRLs) for residues in the Member States, the ISS–CRL frequently prepares test materials to promote comparability of data and support harmonisation of routine analytical procedures. When target values for the analytes are set, the PTSs also provide objective assessment and improvement of the analytical trueness in the daily work.In this context, an interlaboratory comparison for trace elements in tuna fish matrix was organised in cooperation with the Institute for Reference Materials and Measurements (IRMM), Joint Research Centre, European Commission. Freeze-dried tuna fish samples were sent out to the NRLs for chemical elements in the Member States. Participants were requested to carry out at least three independent measurements of the elements As, Cd, Cr, Cu, Fe, Hg, Pb and Zn. The assessment of the proficiency was based on the z-score approach and a relative bias better than or equal to 10% of the target value was deemed to be an acceptable performance for this kind of measurements. On this basis, more than 50% of the laboratories returned accurate results for As, Cu, Fe, Hg and Zn, whereas the analysis of Cd, Cr and Pb appeared to be more problematic.     

Evaluation of 10-years French NRL proficiency tests for lead, cadmium and mercury analysis in foodstuff of animal origin

The French National Reference Laboratory (NRL) for heavy metals in foodstuffs of animal origin at the French Food Safety Agency (AFSSA) regularly organises proficiency tests schemes (PTS) focused on the quantification of the three elements lead (Pb), cadmium (Cd) and mercury (Hg), for the 23 departmental laboratories of the network of laboratories, under its responsibility. The NRL prepares test materials to promote comparability of data and support harmonisation of official analytical procedures in the case of routine analysis. When target values for the analytes are set, the PTS also provide an objective assessment and improvement of the analytical trueness in the daily work of the laboratories.The long-term performance of the network was examined using results of 10 years of PTS in various matrices from different foodstuffs of animal origin (fish, meat and milk products), with 3 different official methods, using Flame- and Electro-Thermal-AAS techniques. In all cases, participants were requested to carry out 3 independent measurements of Pb, Cd and Hg. Moreover, the assessment of the PTS was based on the Z-score approach. From 1998 to 2008, this evaluation applied to 690 results obtained in 41 PTS indicated a frequency distribution of the Z-score value for the three elements Pb, Cd and Hg of 89.2%, 94.5% and 97.7% of acceptable results, respectively. The results of this balance sheet indicated the homogeneity and ability of the laboratories network to provide comparable results of similar quality. Comparison with results obtained by a primary method were presented as complementary information to determine the interest to organize, in the future, PTS based on a certified value.     

Honey as a candidate reference material for trace elements.

The feasibility of producing and certifying new certified reference materials (CRMs) for trace elements in honey was investigated. Preliminary steps for preparation of candidate materials are performed at the Institute for Reference Materials and Measurements, Joint Research Centre of the European Commission (EC-JRC-IRMM). Two different types of honey, Acacia and Eucalyptus, were tested for determination of 10 trace elements. To each type of honey was added a given amount of high purity deionized water to obtain aqueous solutions with an acceptable degree of homogeneity which would require only minimal manipulation before analysis. Average values obtained for the trace elements by means of inductively coupled plasma-based techniques were as follows (in microg/ kg +/- SD): Acacia honey, As, 1.10+/-0.20; Cd, 0.328+/-0.035; Cr, 1.90+/-0.22; Cu, 67.0+/-5; Fe, 215+/-30; Hg, < 0.75; Mn, 82.1+/-6.2; Ni, 21.0 3.0; Pb, 2.30+/-0.25; Se, 9.10+/-1.2; Zn, 167+/-22; Eucalyptus honey, As, 5.99+/-0.10; Cd, 0.592+/-0.074; Cr, 1.50+/-0.07; Cu, 219 24; Fe, 1008+/-114; Hg, <0.75; Mn, 1009+/-51; Ni, 11.3+/-1.5; Pb, 5.00+/-0.40; Se, 5.60+/-0.91; Zn, 791+/-91. When these 2 pilot materials are ready, the certification project will be launched in full compliance with current rules set by EC-JRC-IRMM. If the project is successful, the new CRMs will be put primarily at the disposal of the National Reference Laboratories for trace elements.     

Certified reference material (CRM 414) for the quality control of trace element analysis in plankton

Summary Analyses of plankton are performed by a number of organisations to investigate the transfer and uptake of toxic elements along the trophic chain and to monitor the levels of contamination of different aquatic environments. In order to obtain reliable transfer functions in environmental models or to use plankton as an indicator organism for the assessment of environmental pollution, these analyses should give accurate results. As accuracy requires quality control and the application of certified reference materials (CRMs), a certification campaign has been conducted by the Community Bureau of Reference (BCR). A plankton material was collected in a freshwater pond, lyophilised, homogenised and bottled and its homogeneity and long-term stability were verified. The material (CRM 414) was analysed by a group of 15 selected laboratories having given proof of their adequate QC and using different analytical methods. The contents of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Se, V and Zn are certified. This paper presents the certification work performed.     

Certified reference material for the quality control of cadmium,copper nickel and zinc determination in estuarine water (CRM 505)

Analyses of estuarine water samples are routinely carried out by a number of laboratories to monitor the level of environmental contamination by toxic substances, e.g. heavy metals. A series of interlaboratory studies has been organised by the Community Bureau of Reference, BCR (now renamed Standards, Measurements and Testing Programme) to improve the quality of the determinations of selected trace metals in estuarine water samples. The improvement achieved allowed to produce a reference material (CRM 505) which was certified for its content of Cd, Cu, Ni and Zn. Further improvements were considered to be necessary for the certification of other trace elements, e.g. Pb. This material was collected in the Tagus Estuary, carefully prepared (filtered and acidified) and its homogeneity and long term stability were verified. This paper presents the work performed for the certification of Cd, Cu, Ni and Zn. Indicative values are reported for As, Co, Fe, Mn, Pb and V.     

Certified reference material for the quality control of cadmium, copper nickel and zinc determination in estuarine water (CRM 505)

Analyses of estuarine water samples are routinely carried out by a number of laboratories to monitor the level of environmental contamination by toxic substances, e.g. heavy metals. A series of interlaboratory studies has been organised by the Community Bureau of Reference, BCR (now renamed Standards, Measurements and Testing Programme) to improve the quality of the determinations of selected trace metals in estuarine water samples. The improvement achieved allowed to produce a reference material (CRM 505) which was certified for its content of Cd, Cu, Ni and Zn. Further improvements were considered to be necessary for the certification of other trace elements, e.g. Pb. This material was collected in the Tagus Estuary, carefully prepared (filtered and acidified) and its homogeneity and long term stability were verified. This paper presents the work performed for the certification of Cd, Cu, Ni and Zn. Indicative values are reported for As, Co, Fe, Mn, Pb and V.     

Determination of heavy metal traces in metallic materials with IDMS

Summary Two pure copper samples were analysed for Cr, Ni, Zn, Cd, and Pb with isotope dilution mass spectrometry (IDMS) as a part of a certification campaign of the European Community Bureau of Reference in Brussels. Additionally, one commercially available copper powder was determined for Zn, Cd, and Pb. After dissolution of the sample in aqua regia Pb was separated from the matrix by anodic electrodeposition, the other elements by anion-exchange chromatography. Positive thermal ions were produced in a single-filament ion source using the silica gel technique with phosphoric acid for Zn, Cd, and Pb and with boric acid for Cr and Ni. Most of the heavy metals could be determined with relative standard deviations of about 1% down to the ng/g level. The detection limits were 13 ng/g for Zn, 4 ng/g for Ni, 2 ng/g for Cr, 1 ng/g for Pb, and 0.03 ng/g for Cd. The results were compared with those obtained by another IDMS laboratory and by other methods applied during the certification campaign.

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Bestimmung von Schwermetallspuren in metallischen Werkstoffen mit der massenspektrometrischen IsotopenverdünnungsanalyseTeil 1. Bestimmung von Cr, Ni, Zn, Cd und Pb in reinem Kupfer

     

Analysis of FDA in-house food reference materials with anticoincidence INAA

In-house reference material (IRM) cocoa powder (CCP) has been in use at US Food and Drug Administration laboratories for about 15 years. A single lot of commercial material was originally characterized for 32 elements by several laboratories and five techniques. A unique approach for basis weight determination based upon ambient relative humidity was developed for CCP, eliminating the need for dry weight determinations. The CCP Reference Sheet is updated by incorporating new results approximately every 5 years. The last update occurred in 2006. As part of an effort to revalidate and update values for CCP, anticoincidence instrumental neutron activation analysis (INAA) was used to determine mass fractions for 16 of the originally characterized elements, as well as to provide information on 16 other elements. Results were in very good agreement with 2006 Reference Sheet values. A new candidate IRM, fresh-frozen swordfish (FFSF) powder, was produced by adding inorganic As, Cd, Cr, Hg, Pb, Sb, and Se to liquid nitrogen-frozen commercial swordfish filets which were then homogenized. Portions of FFSF were analyzed by INAA to provide mass fraction and homogeneity information for As, Cd, Cr, Hg, Sb, and Se as well as for eight other elements occurring naturally in the material. Non-homogeneities were ≤2.5 % for As, Br, Cd, and Cs, and ≤1.8 % for Cr, Hg, Rb, Sb, and Se. Certified reference materials DORM-3 Fish Protein powder and fresh-frozen SRM 1947 Lake Michigan Fish Tissue were analyzed as controls.     

Development of an ICP-IDMS method for accurate routine analyses of toxic heavy metals in polyolefins and comparison with results by TI-IDMS

An inductively coupled plasma isotope dilution mass spectrometric (ICP-IDMS) method was developed as a suitable method - with respect to its sensitivity, precision, accuracy, and time-consumption - for the analysis of toxic heavy metal traces (Pb, Cd, Cr, and Hg) in polyolefins. Results for Pb, Cd, and Cr were compared with those obtained by thermal ionization isotope dilution mass spectrometry (TI-IDMS), which was used as a reference method. Because of its high first ionization potential and its high volatility mercury could not be determined by TI-IDMS. A multi-element spike solution, containing isotopically enriched 206Pb, 116Cd, 53Cr, and 201Hg, was used for the isotope dilution step. Decomposition of the polyolefin samples was carried out with concentrated HNO3 at temperatures of about 300 degrees C in a high pressure asher (HPA). This procedure decomposes polyolefins completely and allows isotopic equilibration between sample and spike isotopes. Detection limits of 16 ng/g, 5 ng/g, 164 ng/g, and 9 ng/g were obtained for Pb, Cd, Cr, and Hg by ICP-IDMS using only sample weights of 0.25 g. In different commercially available polyethylene samples heavy metal concentrations in the range of < 5 ng/g to 4 x 10(3) ng/g were analyzed. Both mass spectrometric methods were applied within the EU project "Polymeric Elemental Reference Material (PERM)" for the certification of two polyethylene reference materials. The ICP-IDMS results agreed very well with those of TI-IDMS which demonstrates the accuracy of the ICP-IDMS method also suitable for routine analyses.     

Development of an ICP-IDMS method for accurate routine analyses of toxic heavy metals in polyolefins and comparison with results by TI-IDMS

An inductively coupled plasma isotope dilution mass spectrometric (ICP-IDMS) method was developed as a suitable method – with respect to its sensitivity, precision, accuracy, and time-consumption – for the analysis of toxic heavy metal traces (Pb, Cd, Cr, and Hg) in polyolefins. Results for Pb, Cd, and Cr were compared with those obtained by thermal ionization isotope dilution mass spectrometry (TI-IDMS), which was used as a reference method. Because of its high first ionization potential and its high volatility mercury could not be determined by TI-IDMS. A multi-element spike solution, containing isotopically enriched ²⁰⁶Pb, ¹¹⁶Cd, ⁵³Cr, and ²⁰¹Hg, was used for the isotope dilution step. Decomposition of the polyolefin samples was carried out with concentrated HNO₃ at temperatures of about 300?°C in a high pressure asher (HPA). This procedure decomposes polyolefins completely and allows isotopic equilibration between sample and spike isotopes. Detection limits of 16 ng/g, 5 ng/g, 164 ng/g, and 9 ng/g were obtained for Pb, Cd, Cr, and Hg by ICP-IDMS using only sample weights of 0.25 g. In different commercially available polyethylene samples heavy metal concentrations in the range of < 5 ng/g to 4 × 10³ ng/g were analyzed. Both mass spectrometric methods were applied within the EU project “Polymeric Elemental Reference Material (PERM)” for the certification of two polyethylene reference materials. The ICP-IDMS results agreed very well with those of TI-IDMS which demonstrates the accuracy of the ICP-IDMS method also suitable for routine analyses.     

Producing SI-traceable reference values for Cd, Cr and Pb amount contents in polyethylene samples from the Polymer Elemental Reference Material (PERM) project using isotope dilution mass spectrometry

 The present paper describes the certification of the amount content of Cd, Cr and Pb in two different polyethylene materials within the third phase of the Polyethylene Elemental Reference Material (PERM) project. The analytical procedure to establish the reference values for Cd, Cr and Pb amount contents in these materials is based on isotope dilution mass spectrometry used as a primary method of measurement. Cd and Pb were measured with inductively coupled plasma-mass spectrometry and Cr with positive thermal ionization-mass spectrometry. The decomposition of the polymer matrix was carried out using a high pressure asher. Reference values for amount content, traceable to the SI-system, have been obtained for these three elements in both of the polyethylene samples of PERM. For each of the certified amount content values an uncertainty budget was calculated using the method of propagation of uncertainties according to ISO and EURACHEM guidelines. The measurement procedures, as well as the uncertainty calculations, are described for all three elements. In order to keep the whole certification process as transparent as possible, the preparations of various reagents and materials as well as the sample treatment and blending are described in detail. The mass spectrometry measurements and the data treatment are also explained carefully. The various sources of uncertainty present in the procedure are displayed in the uncertainty budgets. The obtained combined uncertainties for the amount content values were less than 2% relative (k=1) for all investigated elements. The amount contents were in the μmol/kg range, corresponding to mg/kg levels. Received: 21 October 1999 / Accepted: 29 January 2000     

Bioaccumulation of metals and induction of metallo‐ thioneins in selected tissues of common carp (Cyprinus carpio L.) co‐exposed to cadmium,mercury and lead

The concentrations of mercury (Hg), cadmium (Cd) and lead (Pb) at various exposure periods were determined in the gill, kidney, liver and muscle of common carp (Cyprinus carpio L.) co‐exposed to 1.0 µg ml^?1 each of Cd²⁺, Hg²⁺ and Pb²⁺ for up to 10 days. Metallothionein fractions (MTs) in these organs were characterized using the hyphenated technique of size‐exclusion chromatography (SEC) and inductively coupled plasma mass spectrometry (ICP‐MS). After 10 days of exposure, maximum toxic metal concentrations of Hg, Cd and Pb were 10.7 (gill), 0.145 (kidney) and 0.112 µg g^?1_dryweight (gill), respectively. The pattern of accumulation of Hg and Pb was in the order gill > kidney > liver > muscle. In the case of Cd, accumulation was in the order kidney > gill > liver > muscle. Cd and Hg binding MTs were significantly induced in the gill, kidney and liver of all the exposure groups in comparison with the control group (p < 0.05), and the amounts of them increased with the longer exposure time. Despite the higher intracellular Hg concentration and the stronger Hg? SH binding affinity, the amount of Cd‐binding MTs was much higher than that of Hg‐binding MTs. The results indicate that MT synthesis in these organs was clearly metal‐specific. MTs in gill may be used as a bio‐marker to detect the metal pollution caused by Hg and Cd. Zinc and copper binding MTs in the organs of the exposed fish were also increased. This may be due to the MTs' important role in the homeostatic regulation of essential metals and their protective role against the acute toxicity of non‐essential metals. Even though there was considerable accumulation of lead in the organs of the exposed fish, Pb‐binding MT synthesis was non‐significant. Copyright © 2006 John Wiley & Sons, Ltd.     

Trace metal determination in animal tissues: an interlaboratory comparison

Two dried and powdered preparations of narwhal liver and muscle were distributed to 13 laboratories for analysis for Cu, Cd, Zn, Pb, Hg, and Se. Laboratories chose their own methods, using atomic-absorption spectrometry, atomic-emission spectrometry with a direct-current or inductively-coupled plasma, anodic stripping voltammetry (ASV), neutron activation analysis (NAA), and gas chromatography. The coefficients of variation ranged from 2 to 5% for Cu, Cd, Zn, Hg in liver, but were somewhat higher for Zn by ASV and NAA. In muscle, the precision for Zn was similar to that for liver, but was poorer for Cu (8.8%) and Cd (19%). For Pb, the overall precision was 15% and 21% for liver and muscle respectively. Selenium in both tissues was determined with an overall precision of 6-7%, except by NAA, for which it was considerably worse, at 21-26%.     

A new Antarctic certified reference material for trace elements: Adamussium colbecki

The certification of a new reference material for trace elements based on the Antarctic bivalve Adamussium colbecki is reported. This certified reference material (CRM), labelled IRMM 813, was produced in the frame of the Italian National Program for Research in Antarctica (Programma Nazionale di Ricerca in Antartide, PNRA). About 40 kg of the scallop were collected at Terra Nova Bay (Ross Sea). The raw material was freeze-dried, jet-milled and homogenized so as to make it suitable for certification. The elements selected for the certification project were As, Cd, Cu, Cr, Fe, Mn, Ni and Zn. Homogeneity and short- and long-term stability were preliminarily investigated so as to assess the suitability of the freeze-dried mass as a candidate CRM. The candidate material was found to be fit for purpose, thus allowing the following phases of the certification project to be undertaken, in the first place the selection of expert laboratories for the accomplishment of the certification campaign. Eighteen laboratories from twelve countries accepted to participate in the certification project which thus could be successfully completed.