Trace Element Analysis in Forensics

Versatility is one of the key features of Bruker’s S2 PICOFOX total reflection X-ray fluorescence spectrometer. Recently we looked at applications in forensics, which we would like to summarize here for you.

The first application is shooting distance determination, which is an important task during crime scene investigation. It requires trace element analysis of gunshot residue (GSR) deposited around a projectile hole. The major source of GSR is the charge, which contains lead, barium and antimonyin case of conventional ammunition and e.g. copper and zinc in case of copper and lead. Shooting experiments were made by aiming at white scrim from different distances, roughly ranging between 20 cm and 1.5 m. The samples for analysis were then obtained by cutting out fragments of the same size around the bullet hole and dissolving them in aqua regia.

Interesting result is that not only the absolute quantity of GSR correlates to the shooting distance but also the ratio of key elements analyzed. Additionally, the simultaneous determination of all detectable elements using TXRF does allow application of the method if the composition of the primer is unknown. More information can be found in our according lab report.

The second application of interest is the analysis of glass fragments, as can often be found in cases of traffic accidents. Only minute splinters are sufficient for non-destructive fingerprinting using a fast semi-quantitative procedure. The source of the fragments can then be determined through correspondence analysis.

If you would like to learn more about the functional principle of TXRF analysis, please read our TXRF working principle lab report or contact us directly.