Development of an analytical strategy for the determination of 228Th and 232Th in ivory based on the combined use of ICP-MS and α-spectrometry

Elephants are endangered due to the value of their ivory tusks. Therefore, a reliable method for age determination of ivory is of interest for the law enforcement against elephant poachers. The ratio of the specific activities 228 Th/ 232 Th can be used for the age assessment of ivory. In this report, the combination of two complementary detection techniques, namely inductively coupled plasma-mass spectrometry (ICP-MS) and α-spectrometry, for the determination of 228 Th and 232 Th in ivory is presented. Using ICP-MS in addition to α-spectrometry, the uncertainty of the 232 Th determination could be reduced significantly which enabled a more accurate and effective ivory dating.