Determination of trace elements in carbonates by instrumental neutron activation analysis

A systematic non-destructive determination of eighteen trace elements (F, Na, Cl, Sc, Mn, Zn, Br, I, Ba, La, Ce, Sm, Eu, Tb, Yb, Th and U) in carbonate samples by thermal neutron-activation analysis was developed. Three 0.2-0.5 g samples were irradiated for 15 sec (in the case of F), for 3 min (in the case of Na, Cl, Mn, Sr and I) and for 60 hrs (in the case of Sc, Zn, Br, Ba, La, Ce, Sm, Eu, Tb, Yb, Th and U) in the TRIGA MARK II Reactor at a thermal neutron flux of 5x1011ncm-2sec-1 (15 sec and 3 min irradiation) and 1.5x1012ncm-2sec-1 (60 hrs irradiation), respectively. According to the half life of the nuclides formed, the activities were measured with a Ge(Li) spectrometer, after appropriate cooling times. The errors due to the fluctuation of the neutron flux and the counting geometry were minimized by the use of calcium determined previously with EDTA-titration as an internal standard. The interferences from 24Mg(n, p)24Na and 235U(n, fission) reactions were taken into correction. The data of Na, Mn, Zn and Sr were compared with the results obtained by atomic absorption analysis. (T.G.)