SEM-EDS (ASTM E1588-20)
Definition
Scanning electron microscopy with energy-dispersive X-ray spectroscopy, operated under ASTM E1588-20. The reference method for individual GSR particle detection; provides simultaneous morphological and elemental characterisation at single-particle resolution.
- Standard
- ASTM E1588-20
- Technique
- SEM with energy-dispersive X-ray spectroscopy
- Primary use
- Individual gunshot residue particle detection
- Resolution level
- Single-particle morphology and elemental composition
- Data captured
- Simultaneous shape and elemental spectrum per particle
Common questions
Why is SEM-EDS considered the reference method for GSR rather than bulk techniques?+
Bulk methods like AAS or NAA measure total elemental concentration on a sample and cannot confirm the particle morphology diagnostic of firearm discharge. SEM-EDS images each particle's characteristic spherical shape alongside its elemental profile, distinguishing true GSR from environmental lead, barium, or antimony contamination.
What elemental combination does ASTM E1588-20 treat as characteristic of GSR?+
The standard defines particles containing lead, barium, and antimony together, in specific morphological forms, as characteristic of firearm discharge, while particles with only one or two of these elements are classified as merely consistent with GSR and require more caution in interpretation.
How does the method handle lead-free or specialty ammunition?+
ASTM E1588-20 also addresses particle signatures from lead-free primers, which substitute other elements such as strontium, titanium, or gadolinium, so examiners must know the ammunition's likely primer chemistry before ruling GSR present or absent.
Related terms
- AAS (Atomic Absorption Spectrometry)
- An analytical technique measuring the absorption of element-specific wavelengths by atomised sample. For GSR, it quantifies dissolved Pb, Ba and Sb in...
- GFAAS (Graphite Furnace AAS)
- An AAS configuration using an electrically heated graphite furnace to atomise the sample, achieving approximately 100-fold lower detection limits than flame AAS....
- ICP-MS (Inductively Coupled Plasma Mass Spectrometry)
- A bulk elemental quantification technique that dissolves the entire hand swab or SEM stub and measures total element mass per sample. Complements...
- Modified Griess Test
- A contact-transfer colour chemistry test for nitrite-containing propellant combustion residue. Sulphanilic acid undergoes diazotisation with nitrous acid (from NO2 on the target...
- NAA (Neutron Activation Analysis)
- A nuclear analytical technique in which sample irradiation in a research reactor converts stable isotopes to radioactive ones, which are identified by...
- Sodium Rhodizonate
- A chelating agent producing a scarlet-to-red colour with lead ions at acid pH. Applied to entry-wound margins and garment entry holes to...
- SWGGSR Guide (2011)
- The Scientific Working Group for Gunshot Residue 'Guide for Primer Gunshot Residue Analysis by SEM/EDS.' Defines sampling, analysis and reporting requirements for...