U.S. flag

An official website of the United States government, Department of Justice.

Improvements in Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry for Forensic Analysis

NCJ Number
Date Published
July 2013
76 pages
Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) was evaluated for use in the elemental analysis of tapes and copper wires for forensic comparison purposes.
There were five main findings. First, some elements were distributed heterogeneously in the copper wire samples, especially elements at low concentration; therefore, the section analyzed must be large enough to minimize this problem. The applicability of this procedure is not useful for very small samples. Second, many brands of tape samples were readily discriminated. Third, principal components analysis (PCA) methods that use biplots for determining which elemental signals contribute the most to the overall signal variance can be used to obtain additional information from pairwise comparisons. Fourth, large differences in performance between ns and fs laser were not evident for the copper wire samples. The fs laser rapidly ablated through the tape samples, which precluded separate analysis of the back and adhesive sides with this laser. Fifth, it was difficult to ablate only the adhesive side of tape, because the laser removed some of the underlying substrate as well. The project used both a conventional 10 ns laser and a short-pulse (100 fs) laser. PCA was used for data interpretation and for pairwise comparisons of samples based on elemental composition. 5 tables, 8 figures, and 50 references

Date Published: July 1, 2013