A radiochemical method for neutron activation analysis of arsenic in biological samples and its potential use in epidemiology studies

Abstract

Epidemiology studies that examine As toxicity rely on the accurate measurement of As in biological matrices to determine exposure. Accurate measurement of As in biological matrices is challenging by instrumental NAA due to the production of high and variable activities of 24Na, 122Sb and 82Br which contribute to increased background and difficulty quantifying the 76As peak at 559 keV. This paper describes a novel radiochemical NAA method for As analysis in biological matrices. Samples were irradiated at the University of Missouri Research Reactor in a flux of 6.5E + 13 n/cm2/s. Following irradiation samples were transferred to polypropylene tubes with As carrier and digested using a combination of nitric acid and hydrogen peroxide. Arsenic was separated by absorption on magnetite nanocyrstals followed by vacuum filtration. Samples were counted using an automated sample changer and HPGe detector with a Canberra Lynx digital signal analyzer. The accuracy and precision of the RNAA results were evaluated by measuring As in NIST SRM 1575 Pine Needles, 1571 Orchard Leaves, 1566 Oyster Tissue, 1577 Bovine Liver, and NCS DC 73347 Hair. Arsenic was measured in duplicate nail samples by instrumental neutron activation analysis followed by radiochemical neutron activation analysis.