BCR CRMs

BCR CRM 402 Trace Elements in White Clover 0, = 0.456 at 2i.r°C w.c. = 7.52 0.04%. Despite its relatively high value, the water activity is still in the range for long-term stability and major differences in the water content as a consequence of sorption processes are not to be expected. This is supported by the fact that no spoilage has been observed, even though the production was in 1987. 

One example, a candidate matrix material of organotin species in marine water, had stability determined by storage for 120 days at 4°C in the dark, at ambient temperature, and exposed to daylight (Quevauviller and Donard 1991). Frequently storage at different temperatures over at least a i-year period are reported. Examples include organochlorine pesticides (OCPs) in BCR CRM 430, where pork fat was stored at -2o°C, -i-20°C, and -r37°C (van der Paauw et al. 1992). Storage at -20°C, -i-20°C, and -i-4o°C was performed for total and methyl Hg in BCR CRMs 463 and 464, tuna fish (Quevauviller et al. 1994), and metals in BCR CRM 600, EDTA and DTPA-extractable trace metal contents in calcareous soil (Quevauviller et al. 1998m). 

VAN DER Paauw CG, Ribtveld AMJ, Maarse H, Griepink B, Maier EA (1992) Development of pork fat reference material for OCPs BCR-CRM 430. Part I. Preparation, homogeneity and stability. Fresenius J Anal Chem 344 297-300. 

Lichens accumulate trace elements from the atmosphere and thus are frequently used instead of air filters for pollution monitoring. Certification of nine elements (Al, As, Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) by a group of ii selected laboratories was performed in BCR CRM 482 (Lichen) after an inter-comparison on trace elements in samples of this material (Quevauviller et al. 1996b). 

The BCR has also produced a large number of environmental matrix CRMs for PAHs, PCBs, pesticides, and PCDDs/PCDFs as shown in Table 3.12. These matrices include both natural contaminant level matrices as well as natural matrices spiked with low and high levels of contaminants. When viewed together the NIST and BCR CRMs provide a wide range of environmental matrices in which a considerable number of analytes have been assigned certified and reference values. 

Fig. 3.4 Results from the interlaboratory study used for certification of benzo[b]fluoranthene in BCR CRM 088 Sewage Sludge...

Fig. 4.4 Calibration curve for chromium, constructed from measurements of increasing intakes of five different CRMs NIST SRMs 1646 Estuarine sediment, certified content 76 + 3 mg/kg 1632a Coal, certified content 34.4 1.5 mg/kg BCR CRMs 141 Calcareous loam soil, indicative content 75 mg/kg, 142 Light sandy soil, indicative content 74.9 mg/kg and 143 Over fertilized soil, indicative content 228 mg/kg (Kurfiirst 1998b).

Within collaborative work on element concentrations in a number of biological reference materials using solid sampling and other analytical methods, calibration of Cd, Cu, Pb and Zn in BCR CRM 185 Bovine liver with solid CRMs was performed for each element with a reference material of the same matrix, NIST SRM 1577... 

Hg, Fe and Zn were determined with solid sampling GF-AAS, calibration was done with four different suitable BCR CRMs (Pauwels et al. 1993). 

Using a newly developed, transversely heated graphite atomizer and D2-back-ground correction (for details see Sections 2.2 and 4.3), Cd, Pb and Cr were determined in cement and river sediment samples. Of the various calibration approaches applied the best results, also in comparison with wet chemical procedures, were achieved with calibration curves constructed by means of different BCR CRMs with different analyte concentrations and usually n = to individual intakes (Nowka and Muller 1997). 

Mercury in various cement products was determined with a special mercury oven for solid samples. Calibration was performed with four BCR CRMs and one NIST SRM with different Hg content as well as with a reference solution and excellent agreement found (Bachmann and Rechenberg 1991). 

Butyric acid in edible fats GC BCR CRM 164, Anhydrous milk fat Ulberth 1998... 

PCBs in cod, mussel and shrimp from Belgian continental shelf GC BCR CRM 349, PCBs in Cod liver oil Roose et al. 1998... 

I in Danish dairy products ICP-MS BCR CRM 063R, Skim mflk powder Larsen et al. 1999... 

As(III) and As(V) in seafood HGAAS NRCC DORM-1 and DORM-2, Dogfish muscle NRCC TORT-2, Lobster hepatopancreas, BCR CRM 278, Mussel NIST SRM 1566a, Oyster Mimoz et al. 1999... 

Table 6.2 Results from the analysis of a Certified Reference Material (BCR CRM 164 anhydrous milk fat certified for cholesterol content)...

To determine Sb in marine sediments by ETAAS, a direct method was developed based on quantitating the analyte in the liquid phase of the slurries (prepared directly in autosampler cups). The variables influencing the extraction of Sb into the liquid phase and the experimental setup were set after a literature search and a subsequent multivariate optimisation procedure. After the optimisation, a study was carried out to assess robustness. Six variables were considered at three levels each (see Table 2.13). In addition, two noise factors were set after observing that two ions, which are currently present into marine sediments, might interfere in the quantitations. In order to evaluate robustness, a certified reference material was used throughout, BCR-CRM 277 Estuarine Sediment (guide value for Sb 3.5 0.4pgg ). Table 2.13 depicts the experimental setup. 

Table 6.1 Certified contents of chemical species in various BCR CRMs...

Sediment obtained from several sites in Lake Flumendosa, Italy, was collected, homogenised and, following a certification campaign, became available as BCR CRM 601 lake sediment certified for its extractable trace metal contents -sequential extraction (Quevauviller et d., 1997). In sediment CRM 601, concentrations of extractable Cd, Cr, Ni, Pb and Zn are certified in Step 1, but only Cd, Ni and Zn in Step 2, and Cd, Ni and Pb in Step 3. Indicative values are also given for extractable Cu in Step 1 and Pb in Step 2 (European Commission, 1997). The long-term stability of the extractable trace metal content of the reference material was recently demonstrated in a European intercomparison exercise (Lopez-Sanchez, 1998). 

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