DETERMINATION OF AS, CD, CU, HG, MO, SB, AND SE IN BIOLOGICAL REFERENCE MATERIALS BY RADIOCHEMICAL NEUTRON-ACTIVATION ANALYSIS

The elements As, Cd, Cu, Hg, Mo, Sb, and Se were determined in the biological reference materials (RMs) Bowen's Kale, NIST SRM-1577 Bovine Liver, NIST SRM-1549 Milk Powder, and Versieck's 2nd Generation Biological RM Human Serum using two newly developed radiochemical neutron activation analysis (RNAA) procedures. The first is based on sample decomposition in a mixture of H2SO4 + HNO3 + H2O2 and simultaneous extraction of the elements As, Cd - In, Cu, Mo, and Sb by 0.025M Zn(DDC), in chloroform from 2-4M H2SO4 in the presence of 0.01M KI. The second consists of sample decomposition in HNO3 in teflon bombs heated at 150-degrees-C, Hg extraction by 0.01M Ni(DDC)2 in chloroform from about IM HNO3, and Se precipitation by ascorbic acid from about IM HClO4. The RNAA procedures were also used for intercomparison analyses of ''A'' and ''P'' NIST Leaf Materials (NIST candidate SRM-1515 Apple Leaves and NISTSRM-1547 Peach Leaves, respectively), and CZIM Bovine Liver 12-02-01 RM. Very good agreement of results with certified and/or literature values proved the high accuracy of these determinations by the proposed RNAA procedures, even at the sub-ng/g levels.