Analysis and Comparison of Bullet Leads by Inductively-Coupled Plasma Mass Spectrometry

Inductively-coupled plasma mass spectrometry (ICPMS) was used to determine eight elements in 9-mm bullet lead from 12 manufacturers. The purpose was two-fold: 1) to develop a feasible ICPMS method for bullet lead analysis, and 2) to observe the range of variability in elemental compositions for bullet lead from diverse sources. The first of these was significantly aided by reduction of the lead concentration by precipitation; the second was demonstrated by the application of numerical correlation analyses to the data. The results showed that good reproducibility (±5% relative standard deviation) and sensitivity (generally in the sub-part-per-million range) can be obtained. No bullets from different sources had similar elemental signatures, whereas very different signatures could be found within a single box of bullets. Numerical criteria were developed to separate “matching” bullets from all different-source bullets for the subject population.