Ternary Diagram (Pb-Ba-Sb)
Definition
A triangular compositional plot with Pb, Ba and Sb at the three vertices. Particles from conventional primer discharge cluster in the centre; environmental single-element particles appear at the vertices; lead-free particles cluster at different positions.
- Vertices
- Lead (Pb), barium (Ba), antimony (Sb)
- Conventional GSR
- Clusters near the centre
- Environmental particles
- Appear near single-element vertices
- Use
- Distinguishing primer GSR from environmental contamination
Common questions
Why does GSR cluster centrally rather than at a corner?+
A conventional primer discharge deposits particles containing lead, barium and antimony together in roughly comparable proportions, so their combined composition plots near the middle of the triangle rather than at any single vertex.
What does a lead-free result on the diagram indicate?+
Lead-free ammunition uses different primer compounds, so its particles plot in distinct positions away from the traditional Pb-Ba-Sb cluster, which means an analyst must know the ammunition type before interpreting a plotted point.
Related terms
- ASTM E1588-20
- ASTM International standard guide for gunshot residue analysis by SEM-EDS. Defines characteristic, consistent, and commonly-associated particle categories and sampling, analysis, and reporting...
- Automated SEM-EDS
- A robotic scanning electron microscopy workflow using backscattered electron imaging for morphometric screening and automated EDS acquisition for elemental classification. Reduces analysis...
- Characteristic GSR Particle (ASTM E1588-20)
- A particle containing lead, barium and antimony together by SEM-EDS, with spherical morphology and size in the 0.5-10 micrometre range. The highest-specificity...
- DDNP (Diazodinitrophenol)
- A lead-free primary explosive used in some lead-free primer formulations. Produces strontium-antimony or tin-containing GSR particles depending on the oxidiser used.
- Lead Styphnate
- Lead trinitroresorcinate (Pb(C6H(NO2)3O2)), the primary explosive in conventional primer compounds. Co-oxidised with barium nitrate and antimony sulfide to produce the Pb-Ba-Sb triad...
- Organic GSR (OGSR)
- Propellant-derived residues including nitroglycerin, 2-NDPA, 4-NDPA, ethyl centralite and nitrocellulose fragments. Analysed by HPLC or GC-MS, independent of the inorganic SEM-EDS workflow.
- SINTOX
- A lead-free, heavy-metal-free primer formulation developed by DAG (Deutsche Ammunitions- und Geschossfabrik) and Geco in Germany in the 1990s-2000s, replacing lead styphnate...