Griess Test
Definition
A presumptive colour test for nitrite and nitrate ions that uses a diazotisation-coupling reaction to produce a pink-to-red azo dye. Common in explosives field kits but cross-reactive with fertilisers and food residues.
- Detects
- Nitrite and nitrate ions
- Reaction type
- Diazotisation-coupling
- Positive colour
- Pink to red azo dye
- Limitation
- Cross-reactive with fertilisers and food residues
Common questions
Why is a positive Griess test result not confirmatory of explosives?+
The nitrite and nitrate ions the reagent detects are common in everyday materials such as agricultural fertiliser, cured meats, and some food residues, so a positive field result only justifies further presumptive or confirmatory laboratory testing, it cannot on its own establish that an explosive is present.
How is the Griess test applied to a gunshot residue or explosives swab in the field?+
The reagent is applied to a swab or lifted sample from the suspect surface, such as a hand or a fragment near a blast seat, and a colour change to pink or red within a short observation window indicates nitrite or nitrate presence, prompting collection of the item for laboratory confirmation by instrumental methods.
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