CERTIFIED REFERENCE MATERIALS FOR RESEARCH IN ANTARCTICA - THE CASE OF MARINE SEDIMENT

A multielemental certified reference material based on Antarctic marin e sediment was prepared in the framework of the Italian Programma Nazi onale per la Ricerca in Antartide (PNRA, National Program for Research in Antarctica) and was coordinated by the Istituto Superiors di Sanit a (ISS, National Institute of Health). The sediment was collected duri ng the 9th Italian Expedition (1993-1994) in Antarctica in Terra Nova Bay (Ross Sea) at a depth of 80 m, stored at -200C in polyethylene con tainers, and shipped to the ISS. The sediment was subjected to prelimi nary treatment at the Institute for Reference Materials and Measuremen ts (IRMM, Joint Research Centre of the European Commission, Geel Estab lishment, Geel, Belgium). This treatment consisted of sieving, drying, jet milling, sampling, moisture determination, particle size determin ation, and microscopic examination. The final product turned out to co ntain mostly particles smaller than 90 mu m (97% of total mass); parti cles larger than 150 mu m were practically absent. The fraction betwee n 90 and 150 mu m comprised mainly organic material homogeneously dist ributed over the sediment. Five hundred two brown glass bottles (polye thylene insert and plastic screw cap; capacity 120 ml) could be thus f illed with this material, each bottle containing about 75 g of the sed iment. The certification project was accomplished with the active part icipation of eight internationally reputed laboratories from various c ountries (Belgium, Denmark, Hungary, Italy, Spain, and United States). The instrumental techniques resorted to in the certification exercise included cold vapor atomic absorption spectrometry, electrothermal at omization atomic absorption spectrometry, flame atomic absorption spec trometry, inductively coupled plasma atomic emission spectrometry, ind uctively coupled plasma mass spectrometry, isotope dilution inductivel y coupled plasma mass spectrometry, isotope dilution mass spectrometry , neutron activation analysis, solid sampling Zeeman electrothermal at omization atomic absorption spectrometry, and Zeeman electrothermal at omization atomic absorption spectrometry. The certified values establi shed for some trace elements are as follows: Al, 67.1 +/- 3.3 mg/g; As , 4.41 +/- 1.06 mu G/G; Cd, 0.538 +/- 0.027 mu g/g; Cr, 42.1 +/- 3.4 m u g/g; Co, 6.87 +/- 0.31 mu g/g; Fe, 24.4 +/- 0.7 mg/g; Mn, 446 +/- 19 mu g/g; Ni, 9.56 +/- 1.05 mu g/g; Pb, 21.0 +/- 2.9 mu g/g; Zn, 53.3 /- 2.7 mu g/g. In turn, additional elements were quantified by some pa rticipants. Homogeneity of the powdered sediment for the various analy tes is such that intakes as low as 100 mg still show no deviation from the nominal values larger than the attached uncertainty. Intakes of 2 00 mg are, however, recommended to minimize any possible variations in concentration. The product has an average moisture content of 0.30 +/ - 0.03% on delivery. (C) 1998 Academic Press.