PT-WFD: the network of PT providers to support the implementation of the European water framework directive

This paper introduces a newly formed network of proficiency testing (PT) providers, who are active and experienced in the field of PTs with relevance to the water framework directive (WFD). The objective of this new network is to support the implementation of the WFD in Europe, by providing PT schemes that meet the specific requirements of the WFD and which are run and evaluated in a harmonised way. The main value of creating such a network lies in the potential to foster the harmonised performance evaluation of European laboratories involved in WFD monitoring analyses, thus enhancing the equivalence of WFD monitoring data obtained throughout Europe. In its first year the network organised two joint PT rounds, one for volatile organic substances (VOC) and another for selected pesticides from the list of Priority Substances, with greater than 100 water analysis labs from a number of European countries participating.     

Three new mussel tissue standard reference materials (SRMs) for the determination of organic contaminants

Three new mussel tissue standard reference materials (SRMs) have been developed by the National Institute of Standards and Technology (NIST) for the determination of the concentrations of organic contaminants. The most recently prepared material, SRM 1974b, is a fresh frozen tissue homogenate prepared from mussels (Mytilus edulis) collected in Boston Harbor, Massachusetts. The other two materials, SRMs 2977 and 2978, are freeze-dried tissue homogenates prepared from mussels collected in Guanabara Bay, Brazil and Raritan Bay, New Jersey, respectively. All three new mussel tissue SRMs complement the current suite of marine natural-matrix SRMs available from NIST that are characterized for a wide range of contaminants (organic and inorganic). SRM 1974b has been developed to replace its predecessor SRM 1974a, Organics in Mussel Tissue, for which the supply is depleted. Similarly, SRMs 2977 and 2978 were developed to replace a previously available (supply depleted) freeze-dried version of SRM 1974a, SRM 2974, Organics in Freeze-Dried Mussel Tissue. SRM 1974b is the third in a series of fresh frozen mussel tissue homogenate SRMs prepared from mussels collected in Boston Harbor starting in 1988. SRM 1974b has certified concentration values for 22 polycyclic aromatic hydrocarbons (PAHs), 31 polychlorinated biphenyl congeners (PCBs), and 7 chlorinated pesticides. Reference values are provided for additional constituents: 16 PAHs, 8 PCBs plus total PCBs, 6 pesticides, total extractable organics, methylmercury, and 11 trace elements. PAH concentrations range from about 2 ng g^–1 dry mass (cyclopenta[cd]pyrene) to 180 ng g^–1 dry mass (pyrene). PCB concentrations range from about 2 ng g^–1 dry mass (PCB 157) to 120 ng g^–1 dry mass (PCB 153). The reference value for total PCBs in SRM 1974b is (2020 ± 420) ng g^–1 dry mass. Pesticide concentrations range from about 4 ng g^–1 dry mass (4,4-DDT) to 40 ng g^–1 dry mass (4,4-DDE). SRM 2977 has certified values for 14 PAHs, 25 PCB congeners, 7 pesticides, 6 trace elements, and methylmercury. Reference values for 16 additional PAHs and 9 inorganic constituents are provided, and information values are given for 23 additional trace elements. SRM 2978 has certified and reference concentrations for 41 and 22 organic compounds, respectively, and contains contaminant levels similar to those of SRM 1974b. Organic contaminant levels in SRM 2977 (mussels from Guanabara Bay, Brazil) are typically a factor of 2 to 4 lower than those in SRM 1974b and SRM 2978. The organic contaminant concentrations in each new mussel tissue SRM are presented and compared in this paper. In addition, a chronological review of contaminant concentrations associated with mussels collected in Boston Harbor is discussed as well as a stability assessment of SRM 1974a.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Two new marine sediment standard reference materials (SRMs) for the determination of organic contaminants

Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10–20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Certified reference materials for inorganic and organic contaminants in environmental matrices

Chemical measurements often constitute the basis for informed decision-making at different levels in society; sound decision-making is possible only if the quality of the data used is uncompromised. To guarantee the reliability and comparability of analytical data an intricate system of quality-assurance measures has to be put into effect in a laboratory. Reference materials and, in particular, certified reference materials (CRMs) are essential for achieving traceability and comparability of measurement results between laboratories and over time. As in any other domain of analytical chemistry, techniques used to monitor the levels and fate of contaminants in the environment must be calibrated using appropriate calibration materials, and the methods must be properly validated using fit-for-purpose matrix-matched CRMs, to ensure confidence in the data produced. A sufficiently large number of matrix CRMs are available for analysis of most elements, and the group of chemicals known as persistent organic pollutants, in environmental compartments and biota. The wide variety of analyte/level/matrix/matrix property combinations available from several suppliers enables analysts to select CRMs which sufficiently match the properties of the samples they analyse routinely. Materials value-assigned for the so-called emerging pollutants are scarce at the moment, though an objective of current development programmes of CRM suppliers is to overcome this problem.     

Milk and serum standard reference materials for monitoring organic contaminants in human samples

Four new Standard Reference Materials (SRMs) have been developed to assist in the quality assurance of chemical contaminant measurements required for human biomonitoring studies, SRM 1953 Organic Contaminants in Non-Fortified Human Milk, SRM 1954 Organic Contaminants in Fortified Human Milk, SRM 1957 Organic Contaminants in Non-Fortified Human Serum, and SRM 1958 Organic Contaminants in Fortified Human Serum. These materials were developed as part of a collaboration between the National Institute of Standards and Technology (NIST) and the Centers for Disease Control and Prevention (CDC) with both agencies contributing data used in the certification of mass fraction values for a wide range of organic contaminants including polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, polybrominated diphenyl ether (PBDE) congeners, and polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners. The certified mass fractions of the organic contaminants in unfortified samples, SRM 1953 and SRM 1957, ranged from 12 ng/kg to 2200 ng/kg with the exception of 4,4′-DDE in SRM 1953 at 7400 ng/kg with expanded uncertainties generally <14 %. This agreement suggests that there were no significant biases existing among the multiple methods used for analysis.

Certified reference materials for organic contaminants in sewage sludge: a feasibility study

As an answer to the re-evaluation of the European sludge directive, two novel reference materials for organic components in municipal sludge have been produced and test certified for AOX (absorbable organic halogens), PAH (polycyclic aromatic hydrocarbons), NPE (nonylphenol and nonylphenolethoxylates), DEHP (di(2-ethylhexyl)phthalate), bisphenol A, and BFR (brominated flame retardants). The materials were prepared from raw sludge without spiking or mixing of different sludges. The study demonstrated that the technique for the preparation of a suitable reference material, sufficiently homogenous and stable, and with concentration levels that answer the needs of the laboratories and the relevant authorities, can now be presented in detail. The results, furthermore, show there is a need for method validation and standardisation of the measurements of NPEs and certain BFR congeners, and that the development of the laboratory structure in Europe, with fewer and more specialised laboratories, might become a major obstacle when trying to find a sufficient number of laboratories being appropriately proficient for this kind of study in the future.     

European ring exercise on water toxicity using different bioluminescence inhibition tests based on Vibrio fischeri, in support to the implementation of the water framework directive

An inter-laboratory comparison exercise was conducted under the European Union funded project entitled: Screening Methods for Water Data Information in Support of the Implementation of the Water Framework Directive (SWIFT-WFD) and coordinated by the Consejo Superior de Investigaciones Científicas (CSIC), in order to evaluate the reproducibility of different toxicity tests based on the bioluminescence inhibition of Vibrio fischeri, for the rapid water toxicity assessment.For the first time, this type of exercise has been organized in Europe, and using different tests based on the same principle. In this exercise, 10 laboratories from 8 countries (Austria, Cyprus, Germany, Greece, Italy, Portugal, Romania, and Spain) took place, and a total number of 360 samples were distributed.During the exercise, six series of six samples were analyzed along 5 months. Every batch of samples was composed by three real samples and three standard solutions. The real samples were: a raw influent and the effluent of a wastewater treatment plant (WWTP), and a sample from a first settlement of the WWTP spiked with a mixture of toxicant standards.A final number of 330 (91.7%) samples was analyzed, 3300 values in duplicate were collected, and the results for each sample were expressed as the 50% effective concentration (EC₅₀) values calculated through five points of dilution inhibition curves, after 5 and 15 min of incubation times.A statistical study was initiated using 660 results. The mean values, standard deviations (σ), variances (σ²), and upper and lower warning limits (UWL and LWL) were obtained, using the EC₅₀ values calculated with the result from the participating laboratories.The main objectives of this toxicity ring study were to evaluate the repeatability (r) and reproducibility (R) when different laboratories conduct the test, the influence of complex matrix samples, the variability between different tests based on the same principle, and to determine the rate at which participating laboratories successfully completed tests initiated.In this exercise, the 3.93% toxicity values were outliers according with the Z-score values and the Dixon test. The samples with the greater number of outliers were those with the smallest variability coefficient, corresponding to the greater and the smaller toxicity level.No relation was found through the cluster analysis, between the final results and the different commercial devices involved. Testing by multiple commercial devices did not appear to reduce the precision of the results, and the variability coefficient for the exercise was nearby to the average value for past editions carried out at national level, where the different participants used the same commercial device.Stability of samples was also followed during the exercise. While statistical significance differences were not found for the greater part of samples, for the sample from the WWTP influent, a significant decrease of the toxicity value was found along this study. Nevertheless, this was a type of sample with a high toxicity level during all the exercise.On the other hand, in order to obtain the chemical characterization of real samples, those were analyzed by chromatographic techniques, using different sequential solid phase extraction (SSPE) procedures, followed by liquid chromatography coupled with mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS). Good agreement was found between the chemical analysis results and the toxicity level of the samples.     

Standard reference materials (SRMs) for determination of organic contaminants in environmental samples

For the past 25 years the National Institute of Standards and Technology (NIST) has developed certified reference materials (CRMs), known as standard reference materials (SRMs), for determination of organic contaminants in environmental matrices. Assignment of certified concentrations has usually been based on combining results from two or more independent analytical methods. The first-generation environmental-matrix SRMs were issued with certified concentrations for a limited number (5 to 10) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Improvements in the analytical certification approach significantly expanded the number and classes of contaminants determined. Environmental-matrix SRMs currently available include air and diesel particulate matter, coal tar, marine and river sediment, mussel tissue, fish oil and tissue, and human serum, with concentrations typically assigned for 50 to 90 organic contaminants, for example PAHs, nitro-substituted PAHs, PCBs, chlorinated pesticides, and polybrominated diphenyl ethers (PBDEs). Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Experimental design and data evaluation considerations for comparisons of reference materials

The analysis of reference materials (RMs) can help assess the equivalence of chemical measurement processes. When two or more RMs are available for a given measurand, confidently establishing the equivalence of measurement processes requires the RMs to be capable of yielding equivalent results. Evaluating the degrees of equivalence among RMs that differ in analyte quantity and perhaps matrix composition requires an approach other than that used to assess results for samples of a single material. We have more than a decade of experience with an approach that compares the assigned values of RMs to a simple linear model of the relationship between those values and measurement results ideally made under repeatability conditions. In addition to accessing the metrological equivalence of specific RMs, the equivalence of the value-assignment capabilities of the organizations that issue the RMs can also be accessed. This report summarizes our experience with the design of and analysis of studies using this approach and provides numeric and graphical tools for estimating degrees of equivalence. We divide the required tasks into four steps: (1) design, (2) measurement, (3) definition of a reference function, and (4) estimation of degrees of equivalence. We regard the experimental design and measurement tasks as most critical to the eventual utility of the comparison, since creative mathematics cannot fully compensate for poor planning or erratic measurements.     

Critical considerations for the accelerated ageing of high-density polyethylene potable water materials

Accelerated ageing conditions with chlorinated water were identified that minimize variations in solution chemistry and water sorption, and that also enable the interpretation of HDPE physical and chemical changes during 20 week (3884 h) immersion periods. Of the ten conditions tested, three conditions with an alkalinity concentration of 50 ppm as CaCO₃ at pH 6.5 and at 23 and 37 °C performed best. These three conditions exhibited stable pH, free available chlorine, and alkalinity concentration during 20 weeks of HDPE immersion with 72 h changes of ageing solution. HDPE was periodically characterized using differential scanning calorimetry, thermogravimetric analysis, tensile analysis, a density gradient column, moisture analysis, and optical and infrared spectroscopy. Formation of surface carbonyl bonds and gradual reductions in oxidation induction time were detected, as well as water sorption into HDPE. Ageing solution and water sorption monitoring recommendations from this work should be incorporated into accelerated ageing protocols and considered when characterizing aged PE drinking water pipe.     

Development of frozen whale blubber and liver reference materials for the measurement of organic and inorganic contaminants

Summary Fresh frozen homogenates of pilot whale blubber and liver tissue were prepared for use as control materials for the determination of organic and inorganic contaminants in marine mammal tissue analyses. The blubber material was analyzed to determine 30 polychlorinated biphenyl congeners and 16 chlorinated pesticides using gas chromatography with electron capture detection and gas chromatographymass spectrometry. A total of 39 trace elements and methylmercury were determined in the liver homogenate using instrumental neutron activation analysis, voltammetry, and cold vapor atomic absorption spectroscopy. The preparation and analysis of these two tissue materials are part of the development of marine mammal tissue reference materials.     

Improvements in efficiency of production and traceability for certification of reference materials

Issues of current interest to certified reference material producers are addressed. Alternative strategies for certification of matrix reference materials are discussed and the benefits of adopting a flexible, cost-effective approach are described. The difficulty of undertaking homogeneity testing where certification is to be carried out with definitive techniques capable of providing very small measurement uncertainty is discussed. Methodology is described which combines conventional screening of the candidate material for homogeneity with an additional, precise assessment of homogeneity based on isotope dilution mass spectrometry measurements. A systematic procedure for evaluating the commutability (horizontal traceability or scope) of matrix reference materials has been evaluated and shows that in some circumstances matrix effects may be less pervasive than is generally believed. This offers the possibility, especially for trace analysis applications, of more efficient use of existing reference materials without compromising measurement reliability. Vertical traceability of matrix reference material data is of growing interest but is difficult to achieve with present interlaboratory certification exercises. A modification is described which attempts to address this issue. It also offers the possibility of improved identification of outliers and reduced variation of data between the participating laboratories.Presented at BERM-9—9th International Symposium on Biological and Environmental Reference Materials, 15–19June 2003, Berlin, Germany     

Metrological concept for comparable measurement results under the European water framework directive: demonstration of its applicability in elemental analysis

Within the scope of a project of the “European Association of National Metrology Institutes??(EURAMET), a European metrological dissemination system (network) providing traceable reference values assigned to matrix materials for validation purposes is described and put to the test. It enables testing laboratories (TL) to obtain comparable results for measurements under the “EU Water Framework Directive 2000/60/EC??(WFD) and thus, to comply with a core requirement of this very directive. The dissemination system is characterized by the fact that it is available to all laboratories throughout Europe which intend to perform measurements in the context of the WFD and that it can ensure sustainable metrological traceability to the International System of Units (SI) as a reference point for the measurement results. This dissemination system is set up in a hierarchical manner and links up the level of the national metrology institutes (NMI) with that of the TLs via an intermediate level of calibration laboratories (CL) by comparison measurements. The CLs are expert laboratories with respect to the measurement of the analytes considered here (within the project, the CLs are called potential calibration laboratories (PCL)) and are additionally involved in the organization of comparison measurements within the scope of regional quality assurance (QA) systems. Three comparison measurements have been performed to support the approach. A total of about 130 laboratories participated in this exercise with the focus on the measurement of the priority substances Pb, Cd, Hg, and Ni defined in the WFD. The elemental concentrations in the water samples roughly corresponded to one of the established environmental quality standards (EQS), the annual average concentration (AA-EQS), which is defined in the daughter Directive 2008/105/EC of the WFD. It turned out that a significant number of TLs still need to improve their measurement methods in order to be able to fulfill the minimum requirements of the WFD, in particular, with regard to the elements Cd and Hg probably due to their low EQS values. Furthermore, it became obvious that the hierarchical dissemination system suggested here actually corresponds to the measuring capabilities of the three participating groups (NMIs, PCLs, and TLs).     

Development of in-house reference materials for determination of inorganic polysulfides in water

In-house reference materials (IHRMs) for determination of inorganic polysulfides in water have been developed. The determination is based on the polysulfides derivatization with a methylation agent followed by GC/MS or HPLC analysis of the difunctionalized polysulfides. Therefore, the IHRMs are synthesized in the form of dimethylated polysulfides containing from four to eight atoms of sulfur. The composition of the compounds is confirmed by NMR and by the dependence of the HPLC retention time of the dimethyl polysulfides on the number of sulfur atoms in the molecule. Stability of the IHRMs is studied by HPLC with UV detection at 230 nm. Carbon tetrachloride solutions of the dimethyl polysulfides are stable at –20°C for 2 weeks, while their solutions in a mixture of acetonitrile and formic acid, 1:1, are stable even at +5°C for 3 weeks. The total sulfur content is controlled by the IHRMs oxidation with perchloric acid in high-pressure vessels (bombes) followed by determination of the formed sulfate using ICP-AES. Certified values of the dimethyl polysulfide concentrations are in the range of 416–3,327 ppm.Presented at the Second International Conference on Metrology—Trends and Applications in Calibration and Testing Laboratories, 4–6 November, 2003, Eilat, Israel     

Availability of reference materials: COMAR the database for certified reference materials

COMAR is the international database for certified reference materials. A new user-friendly web-based version, COMAR², has been developed by BAM and CONET Consulting AG which will be available in December 2002. The advantages of COMAR² are briefly explained.Presented at the International ILAC/IAF Conference on Accreditation in Global Trade, 23-25 September 2002, Berlin, Germany     

Laboratory accreditation in Italy for reference solution production of sucrose in water

The accreditation of Chemifarm srl laboratory for the calibration of two characteristics on the same aqueous solution has been achieved. The process has been executed by the Italian accreditation body for calibration laboratories (SIT). This is the first example of a producer of certified reference solutions in Italy. The solutions are mixtures of sucrose in water at several concentrations and are characterised for refractive index in the range of 1.33299 to 1.38115 and for mass fraction of sucrose in the range of 0 to 30 (commercially expressed in Brix degrees). Both traceability paths, obtained through refractometric and gravimetric methods, are reported. Furthermore, the paper describes the approach adopted to match the criteria based on ISO Guide 34 and ILAC-G 12, the documents with requirements for certified reference material producers, in compliance with those of ISO/IEC 17025, the norm for the laboratory accreditation.     

Planning and certification of new multielemental reference materials for research in antarctica

The adoption of the principles of Good Laboratory Practice (GLP) and the implementation of the ensuing procedures for quality assurance (QA) and quality control (QC) of analytical determinations are nowadays deemed essential to the achievement of sound, credible and comparable experimental information. This is certainly also applicable to research projects currently being carried out in the antarctic continent, in particular as regards investigations on global change phenomena. Worldwide investments made so far in this field do require in fact that reliability of data be optimized so as to allow for a harmonized assessment of ongoing trends. In this context the Italian National Programme for Research in Antarctica has recently launched a project for the preparation of new multielemental certified reference materials (CRMs) to be used for QC of analyses performed on environmentally significant materials. The suitability of CRMs to verify the accuracy of experimental measurements acknowledgedly depends, among others, on the degree of similarity of their matrix composition and analyte levels to those expected for real samples. From this standpoint three CRMs are planned, namely: i) marine sediment certified for Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn and Zn; ii) ocean water certified for Cd, Cr, Cu, Fe, Hg, Mn, Ni and Pb; iii) krill certified for As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn and Zn. Regarding the first two matrices, amounts of ca. 100 kg and ca. 1001, respectively, have been collected during the IX (1993–1994) antarctic expedition, while krill was taken in the course of the X (1994–1995) campaign. The pretreatment of sediment has been accomplished in terms of homogenization, stabilization and characterization of the preliminary ground mass. Approximately 500 bottles, each containing 75 g of material are now ready for distribution to interested laboratories involved in chemical measurements of antarctic matrices, whereas ocean water and krill will follow at a later stage. Finally, depending on circumstances, also the certification of organochlorine compounds in the same materials will be attempted.     

A new approach to the preparation of biological reference materials for trace metals

Summary Preparation and certification of a new, nondefatted biological reference material (RM) for trace metals is reported. LUTS-1 is a homogeneous slurry of lobster hepatopancreas containing 85% (w/w) moisture and 8.2% (w/w) lipids (55% dry weight basis). This RM should prove of considerable use in validating analytical procedures involving faunal field samples containing significant lipid content.

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Neue Methode zur Herstellung von biologischen Referenzmaterialien für Spurenmetalle