Analysis of elemental and isotopic variation in glass frictionators from 0.22 rimfire primers

Kelsey E Seyfang; Hilton J Kobus; Rachel S Popelka-Filcoff; Andrew Plummer; Charles W Magee Jr; Kahlee E Redman; K Paul Kirkbride

doi:10.1016/j.forsciint.2018.10.017

Analysis of elemental and isotopic variation in glass frictionators from 0.22 rimfire primers

Forensic Sci Int. 2018 Dec:293:47-62. doi: 10.1016/j.forsciint.2018.10.017. Epub 2018 Oct 29.

Authors

Kelsey E Seyfang¹, Hilton J Kobus², Rachel S Popelka-Filcoff³, Andrew Plummer⁴, Charles W Magee Jr⁵, Kahlee E Redman⁶, K Paul Kirkbride⁷

Affiliations

¹ College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, 5042 Adelaide, South Australia, Australia. Electronic address: Kelsey.Seyfang@flinders.edu.au.
² College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, 5042 Adelaide, South Australia, Australia. Electronic address: Hilton.Kobus@flinders.edu.au.
³ College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, 5042 Adelaide, South Australia, Australia. Electronic address: Rachel.PopelkaFilcoff@flinders.edu.au.
⁴ Forensic Services Branch, South Australia Police, South Australia 5000, Australia. Electronic address: Andrew.Plummer@police.sa.gov.au.
⁵ Australian Scientific Instruments, Fyshwick, 2609 ACT, Australia; Australian National University, Research School of Earth Sciences, ACT 0200, Australia; Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia. Electronic address: Charles.Magee@ga.gov.au.
⁶ Forensic Science SA, Divett Place, Adelaide, South Australia 5000, Australia. Electronic address: Kahlee.Redman@sa.gov.au.
⁷ College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, 5042 Adelaide, South Australia, Australia. Electronic address: Paul.Kirkbride@flinders.edu.au.

PMID: 30396149
DOI: 10.1016/j.forsciint.2018.10.017

Abstract

The majority of 0.22 calibre rimfire ammunition available in Australia, and overseas, tends to use glass powder rather than antimony sulfide frictionator in the primer. This glass can be the nucleus of a GSR particle, with other primer components condensing around and onto the glass structure. As the composition of glass frictionator remains largely unaltered during ammunition discharge [1] there is the possibility that frictionator composition could be used in GSR examinations to either correlate or discriminate between samples, thereby providing valuable information to an investigation. In this study, the composition of glass frictionator from a wide variety of ammunition was analysed by time-of-flight - secondary ion mass spectrometry (ToF-SIMS), sensitive high-resolution ion microprobe (SHRIMP) and scanning electron microscopy - energy dispersive X-ray spectrometry (SEM-EDS). Refractive index (RI) was measured using glass refractive index measurement (GRIM). Across the population of ammunition studied, it was found that the elemental and isotopic composition of frictionator varied. ToF-SIMS was able to discriminate 94.1% of brands in a pairwise comparison and SEM-EDS achieved a pairwise discrimination power of 79.4%. If SHRIMP was combined with the other two techniques, 95.6% of brands could be discriminated. Refractive index measurements supported the elemental data showing that there appeared, in most cases, to be only one population of glass within a cartridge. The results suggest that there is scope for frictionator analysis to contribute valuable, new capability to forensic GSR examinations.

Keywords: Elemental composition; Glass frictionator; Glass-containing gunshot residue (gGSR); Gunshot residue (GSR).