- 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
Chemistry
Home > Gunshot Residue and Distance Determination > Examination > Chemical Testing > Chemistry
The chemistry of the Sodium Rhodizonate Test is comprised of the following process:
- The questioned area is sprayed directly with a saturated solution of sodium rhodizonate in distilled or deionized water.
- A buffer solution (pH 2.8) consisting of sodium bitartrate and tartaric acid in distilled or deionized water is then sprayed on the area.
Any pink reaction which results may indicate lead or a number of other possible heavy metals. The presence of lead may be confirmed through an additional step. - A dilute solution of hydrochloric acid is applied by spraying the area.
The color results are dependent on the degree of acidity and the presence of lead. If the pink area changes to a blue-violet color, the presence of lead is confirmed.
