Candidate Certified Reference Material Research Articles

Certified reference materials (CRMs 479 and 480) for the quality control of nitrate determination in freshwater

Monitoring of freshwater and groundwater is routinely performed to control the level of contamination by a wide variety of trace and major constituents, including nitrates. In order to verify the quality of such determinations, the Standards, Measurements and Testing Programme (formerly BCR) has started a project, the first step of which was to evaluate the performance of European laboratories in an interlaboratory study and the second phase was a certification campaign of nitrate in two artificial freshwater samples. This paper presents an overview of the results of the interlaboratory evaluation and gives details of the preparation of the candidate certified reference materials (CRMs), the verification of their homogeneity and stability, the techniques used in the certification and the certified values. Two CRMs were produced: CRM 479 containing a low nitrate content (214 ± 4 µmol kg–1 or 13.3 ± 0.3 mg kg–1) and CRM 480 containing a high nitrate content (885 ± 13 µmol kg–1 or 54.9 ± 0.8 mg kg–1).

Preparation of candidate certified reference materials for the quality control of EDTA-and acetic acid-extractable trace metal determinations in sewage sludge-amended soil and terra rossa soil

The determination of extractable trace metal contents in soil using single extraction procedures is currently performed in many laboratories to assess the bioavailable metal fraction (and related phytotoxic effects) and the accessability to the environment (e.g. contamination of ground waters). Owing to the need for validation of the extraction schemes used and of the analytical techniques, the EC Measurements and Testing Programme (formerly BCR) has organized a project for improving the quality of determination of extractable trace metal contents in soil, the first step being an interlaboratory study to adopt common extraction procedures and the second being a certification campaign to certify two soils for their extractable trace element contents following these procedures. This paper gives a brief overview of the project organisation and describes the preparation, homogeneity and stability studies of two soil candidate reference materials (sewage sludge-amended and terra rossa soils).

Trace elements in food reference materials: compositional and analytical perspectives

Selection criteria for production of food reference materials need to simultaneously consider realistic proximate matrix compositions, emerging trends for the nutritional and toxicological effects of less-emphasized trace elements (e.g., B, Li, Si, and V), chemical speciation (especially for As, Hg, Se, and Sn), and analyte certification requirements from the analyst's point of view. For the most part, currently available Certified Reference Materials (CRMs) do not meet many of these needs. Candidate CRMs with relevant concentrations of trace elements could be chosen from similar foods with different proximate compositions (e.g., fat content of milk products, meat, or soya flour). Explicit guidance must accompany CRMs so that variations in measured trace element concentrations arising from procedural lapses and basis weight are avoided.

Interlaboratory programme for the quality control of nitrate determination in freshwater

Analyses of freshwaters and groundwaters are routinely performed to monitor the level of contamination by, e.g., nitrates. To verify the quality of such determinations, the Community Bureau of Reference (BCR) has organised an interlaboratory exercise which allowed to identify most of the pitfalls observed in the determination of nitrate at three levels of concentrations (0.5, 8 and 53 mg kg −1). In addition, this first step enabled the BCR to study the feasibility of the preparation of candidate certified reference materials (CRMs) for the determination of nitrate in freshwater. The materials used in this exercise were carefully prepared and their homogeneity and stability were verified by using a flow-injection analysis technique developed for this purpose. This paper presents the main results of the intercomparison.

Solid sampling Zeeman atomic absorption spectrometry in production and use of certified reference materials

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