The successful application of detonation nanodiamond (DND) to the development of new technologies depends on its purity. However, the number and content of minor elemental impurities within DND has not been seriously considered by researchers due to the absence of simple, sensitive, and robust methods for the direct analysis of such materials. Recently, a breakthrough in the direct and sensitive analysis of up to 55-60 minor elemental impurities in DND at concentration levels as low as 10-8 wt.% was achieved using inductively coupled plasma mass-spectrometry (ICP-MS). Within this chapter, the performance of ICP-MS for this application is compared with other methods such as inductively coupled plasma - atomic emission spectroscopy (ICP-AES) and neutron activation analysis (NAA). The high sensitivity and precision of ICP-MS facilitates the identification of contamination sources and consequently points the way towards significant improvements in existing purification technologies for DND.