- 01: Introduction
- 02: History
- 03: Propellants, Firearms, and Ammunition Development
- 04: Modern Firearms Manufacture
- 05: Small Arms Ammunition
- 06: Evidence Handling Procedures
- 07: Equipment and Instrumentation
- 08: Examination of Firearms
- 09: Cartridge and Shotshell Examination
- 10: Characterization and Evaluation of Fired Projectiles
- 11: Bullet Comparison and Identification
- 12: Gunshot Residue and Distance Determination
- Introduction
- Objectives
- AFTE Knowledge and Ability Factors
- Powders and Residues
- Examination
- Distance Determination
- Significance of Results
- Contact Shot
- Nitrite Residues
- Vaporous Lead Residues
- Residues Consistent with the Passage of a Bullet
- Residues Consistent with the Discharge of a Firearm
- Interpretation Challenges
- Reproduction of Results
- Nitrite Residue Patterns
- Shot Patterning
- Chemical Testing
- Shot Pattern Reproduction
- Selected Bibliography
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
Reagents and Test Media
Home > Gunshot Residue and Distance Determination > Examination > Chemical Testing > Reagents and Test Media
Hydrochloric acid
The following reagents and test media are required for the Sodium Rhodizonate Test:
- Saturated solution of sodium rhodizonate dissolved in distilled or deionized water
- Buffer solution of 2.8 pH consisting of sodium bitartrate and tartaric acid in distilled or deionized water
- Solution of hydrochloric acid (5 percent) in distilled or deionized water
- A known source of lead
Sodium Rhodizonate Solution
Add a sufficient amount of distilled or deionized water to a small amount of sodium rhodizonate in a small beaker to form a saturated solution that is approximately the color of dark tea. The solution is saturated if a slight amount of sediment remains in the beaker after stirring with a glass stirring rod. The solution is usually ineffective after one hour.
2.8 pH Buffer Solution
- Dissolve 29.3 grains (1.9 grams) of sodium bitartrate and 23.1 grains (1.5 grams) of tartaric acid per 100 mL of distilled or deionized water. Heat on a hot plate while agitating with a magnetic stirrer to create the solution quickly.
- Store in a sealed container labeled according to laboratory protocol. The shelf life of the solution is limited.
Hydrochloric Acid Solution
- Combine 5 mL of concentrated hydrochloric acid with 95 mL of distilled or deionized water. Carefully pour the acid into the water to preclude spattering of acid.
- Store in a sealed container labeled according to laboratory protocol.
