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Modified Griess Test

Home > Gunshot Residue and Distance Determination > Examination > Chemical Testing > Modified Griess Test

The Modified Griess Test is a chemically specific chromophoric (color-producing) test for the presence of nitrite compounds, such as those produced by the burning of smokeless powder. This test focuses on the analysis of the size and density of patterns of nitrite residues on a victim’s clothing or other objects as well as their reproduction at known distances using the suspect’s firearm in combination with the same type of ammunition.

This test has superseded the original Griess Test in that it does not involve the use of Marshall’s Reagent, a solution suspected of being a carcinogen. Essentially, the new test avoids the use of N-(1-naphthyl)-ethylenediamine dihydrochloride, a component of Marshall’s Reagent. This modification is safer, provides more vivid color results, and uses less expensive reagents and test media than the original Griess Test.

It is important to keep in mind that the Modified Griess Test does not yield a positive result for nitrate compounds, such as completely unburned smokeless powder particles. When smokeless powder burns or partially burns, nitrite compounds are formed, which may be detected by the use of the Modified Griess Test.

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