What is dermal nitrate test – in forensic science

A presumptive test for the presence of gunshot residue (gsr), also called the paraffin test, that is no longer used. Whenever a person fires a gun, traces of residue are transferred to the hands. The dermal nitrate test was based on detecting the nitrate ion (NO3), an ingredient in propellants used in ammunition. For the test, the hands of the suspect were painted with hot wax (paraffin) that was allowed to dry. The cast was then removed and tested using the reagent diphenylamine combined with sul-furic acid (H2SO4). Locations on the cast that showed a blue color indicated the possible presence of nitrate. In addition to gunshot residue, nitrates are common in many materials that could be found on the hands, including tobacco, cosmetics, fertilizers, and urine. This large number of potential false positives led to the test being abandoned since it was not sufficiently specific to GSR.