5% HNO3 Swab
Definition
A cotton or polyester swab pre-wetted with 5% nitric acid, used to collect dissolved GSR for atomic absorption spectrometry or ICP-MS. Recovers lead, barium and antimony from the hand surface as dissolved ions.
- Acid concentration
- 5% nitric acid
- Target elements
- Lead, barium, antimony
- Downstream method
- AAS or ICP-MS
- Sample source
- Hand surface swab
Common questions
How is this different from the adhesive stub sampling used for SEM-EDS?+
The acid swab dissolves whatever GSR is on the skin into solution, so it only yields a bulk concentration of Pb, Ba and Sb. It destroys particle morphology, unlike an adhesive stub, which preserves individual particles for SEM-EDS imaging.
Can a positive result from this swab confirm gunshot residue on its own?+
Not definitively. Because it measures dissolved elemental levels rather than intact particles, it cannot show the fused, spherical morphology that distinguishes true GSR from other environmental sources of the same elements.
Related terms
- Carbon-Tape Stub (Tri-Mark)
- A standard SEM-format aluminium or plastic pin stub bearing conductive double-sided carbon tape, used to collect GSR from hands and surfaces for...
- Environmental Control Stub
- A blank carbon-tape stub collected from the collection environment (table surface, custody cell, vehicle seat) to establish background particle levels in the...
- NABIS (National Ballistics Intelligence Service)
- The UK agency responsible for managing ballistic evidence including GSR analysis, operated by the National Police Chiefs' Council. Issues guidance on GSR...
- Persistence Half-Life (GSR on Hands)
- The time after which approximately half of the initial particle count has been lost from the hand surface. Published studies (Cardinetti 2004,...
- Secondary Transfer
- The movement of a glass fragment from a primary surface (which contacted the broken glass) to a secondary surface (which contacted the...
- Tertiary Transfer
- Transfer of GSR from a secondary surface (a person who received particles via handshaking) to a third surface. Documented at low levels...