Tuna Fish Material

The tuna fish material (CRM 627) was prepared by the Joint Research Centre, Environment Institute, of Ispra (Italy) whereas the arsenobetaine solution (CRM 626) was prepared by the Laboratoire de Chimie Analytique et Minerale in Strasbourg (France) [134]. 

The material was obtained from the dty of Venice (fish removed from the fish market, owing to its too high content in mercury). The fish were caught in the Messina strait, kept frozen for approximately four weeks, dissected and the dorsal muscles were taken these were minced and freeze-dried, ground in a zirconium dioxide mill, passed over a 125 pm sieve and the fraction 125 pm was discarded. 

The homogeneity was verified by repeated determinations of total As, arsenobetaine and DMA. The total As content was determined by HG-QFAAS after microwave assisted digestion, whereas DMA was determined by HPLC-ICP-MS. The within-bottle homogeneity was assessed by 10 determinations in each of two bottles, and the between-bottle homogeneity was evaluated by two determinations out of each 20 bottles the method uncertainty was evaluated by five replicate determinations of a digest or extract solution. The within- and between-bottle CV ranged from 0.5 to 1.2% for total As, from 2.1 to 5% for arsenobetaine, and from 7.1 to 10.6% for DMA, which was comparable to the method uncertainty (respectively 2.6, 3.1 and 6.8%) therefore, no inhomogeneity was suspected at a level of 0.3 g for total As and 1 g for As species, and the material was considered to be suitable for use as a CRM. 

The stability of arsenobetaine and DMA in tuna fish was tested over a period of 9 months at — 20°C, +20 °C and +40 °C by performing one determination on each of live bottles stored at different temperatures after 1, 3, 6 and 9 months. The reproducibility of the analytical method (same as the one used in the homogeneity study) was verified by determining a portion of raw extract (prepared at the beginning of the study and stored at — 20°C) at each occasion of analysis. In addition, the stability of the material and of the raw extract was also verified by qualitative control of the chromatograms no unexpected peaks containing arsenic were detected. The results showed that no instability could be demonstrated for both arsenobetaine and DMA at +20 °C and+40 C [134]. 

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Quevauviller Ph, Drabaek I, Muntau H, Griepink B (1994) The certification of the contents (mass fractions) of total and methyl mercury in two tuna fish materials CRMs 463 and 464. 

Quevauviller, Ph., Drabask, I., Muntau, H. and Griepink, B. (1993c) Improvements in the MeHg determination prior to the certification of two tuna fish materials. Appl. Organometal. Chem., 7, 413. 

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). 

Quevauviller Ph, and Maier EA (1999) Interlaboratory studies and certified reference materials for environmental analysis - the BCR approach. Elsevier, Amsterdam Quevauviller Ph, Drabaek I, Muntau H, Biahchi M, Bortoli A, and Griepink B (1996a) Certified reference materials (CRMs 463 and 464) for the quafity control of total and methyl mercury determination in tuna fish. Trends Anal Chem 15 160-167. 

A wide variety of reference materials is now available, covering several different kinds of natural matrix such as food (e.g. milk powder), human tissues (e.g. liver), marine biological materials (e.g. tuna fish) and soils and sediments. The radionuclides of interest cover naturally occurring ones (e.g. Ra), fission products... 

Accuracy and Analytical Quality Control Aspects The analysis of certified reference materials (CRMs) following the same analytical procedures was performed for assessment of the accuracy of the procedure and for quality control (QC). Yet, the available CRMs are mostly freeze-dried, not fresh or deep-frozen. In Table 22.3 an overview of CRMs in a seafood matrix with respect to organic Hg is given. It is certainly beneficial that more and more CRMs are becoming commercially available. Recently, a new CRM for trace elements in a matrix of lyophilized tuna fish (IMEP-20) has been produced [44]. Apart from total Hg (4.32 mg kg-1 dry mass) and Me-Hg (4.24 mg kg-1 dry mass), this material is also certified for other elements such as As, Pb, and Se. 

Tuna fish (reference material) Chromium speciesd Store at 20 and 40° C in the dark 12 months 20... 

At present, only a few CRMs for arsenic species are available, these are from Institute for Reference Materials and Measurements (IRMM) BCR 626 (Arsenobetaine solution), certified 1031 6 mg kg , and BCR 627 (Tuna fish) certified 52 3 pmol kg arsenobetaine, 2.0 ... 

The certification procedure for seven trace metals (Ba, Ca, Li, Mg, Mn, Na and Sr) in the certified reference material FEBS-1 (National Research Council Canada, Institute for National Measurement Standards, Ottawa, Canada) based on fish otolith matrix by isotope dilution - ICP-MS in comparison to ICP optical emission spectrometry and X-ray fluorescence analysis, is described by Sturgeon et al4X The isotope dilution technique is also employed for species analysis in biological systems,46 e.g., for the determination of mercury species in tuna material,54 or in aquatic systems using cold vapour ICP-MS.55... 

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