Application of Isotope Dilution for the Determination of Thorium in Biological Samples by Inductively. Coupled Plasma Mass Spectrometry

Abstract

The applicability of isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) was examined for Th in biological samples. A naturally occurring isotope of Th (Th-230) was used as the spiking isotope (called "tracer" in the text). The concentration of Th-230 in the final sample solution was about 50-60pg/ml; an isotope ratio of 232/230 could be measured with a relative standard deviation of less than 2%. The error magnification depended on the amount of Th-232 being concomitant with the Th-230. Though it was shown that one ng of Th-232 could be determined with reasonable precision with a tracer of the present purity, more care should be taken to reduce any source of systematic error.