Highly accurate radiochemical neutron activation analysis of arsenic in biological materials involving selective isolation of arsenic by hybrid and conventional ion exchange

A highly accurate (definitive) radiochemical neutron activation analysis (RNAA) method was developed for the determination of traces of arsenic (As) in biological materials. It consists of the following steps: (a) irradiation in the nuclear reactor; (b) microwave-assisted sample digestion; (c) quantitative and selective radiochemical separation of arsenates on hydrated ferric oxide nanoparticles dispersed in a macroporous cation exchanger, preceded by a conventional strongly acidic cation exchanger column, and (d) gamma-ray spectrometric measurement of 76 As. The suitability and accuracy of the method was demonstrated by analysing several certified reference materials. The detection limit is 8 ng g −1 . The standard uncertainty in the determination of As in oriental tobacco leaves is around 3.4%. This, together with its compliance with several other formal requirements, makes the method comparable to primary methods based on isotope dilution mass spectrometry.