Skip to main content

Table 3 Color test performed for the detection of GSR

From: Gunshot residue detection technologies—a review

Color test/references Constituent detected Color change Merits Demerits
Dermal nitrate test (Forensic ballistics, Chemical analysis of gunshot residues (GSR), n.d.) Nitrates Blue color spots 1. Major advantage of this test is that it can be applied to all nitro groups’ compound analysis. 1. Disadvantage is that it give false positive result in presence of tobacco, leguminous plants, fertilizers etc.
Walker’s test/Griess test (Griess, 1858) Nitrites Red color spots 1. Advantage in using this technique is that it can be helpful in detecting the nitrites in partially burnt and unburnt propellants. 1. Disadvantage is many compounds other than nitrocellulose propellants can give positive reaction e.g. Urine, fertilizer, face powder etc.
Modified Griess test Nitrites Pink color 1. Major advantage of this technique is that it can be performed within few minutes and found to be better than dermal nitrate test. 1. It can be applied to detect nitrites only but not for GSR.
Harrison and Gilroy’s Test (Harrison & Gilroy, 1959) Pb, Sb, Ba Sb—orange ring
Pb—blue color
Ba—red color
1. More successful than dermal nitrate test as it cause less false positive cases.
2. Another advantage is that it can be easily applied to detect GSR samples on hand swabs.
1. Interference with other materials at the SOC can be obtained.
Sodium rhodizonate test (Steinburg et al., 1984; Bartsch et al., 1996) Pb
Ba
Blue to violet (pH 7)
Bright red color (pH 2.8)
Red-brown (any pH)
1. Major advantage of this color test is that it can detect lead and its form in trace level. 1. Major disadvantage with this is it cannot be applied for Ba detection
Lunge test (Forensic ballistics, Chemical analysis of gunshot residues (GSR), n.d.) Nitrocellulose/nitrites Deep blue color 1.Major advantage is it can be performed in few minutes 1. Major disadvantage is it can give positive reaction with other everyday used chemicals.
2. Not further applied for detecting GSR on hand swabs.
Di-thio-oxamide (DTO) test (Forensic ballistics, Chemical analysis of gunshot residues (GSR), n.d.) Copper, nickel, cobalt Copper—very dark-green coloration, nickel—pink to violet color, and cobalt—brown color 1. Advantage in using this color test is that it can be applied to detect Cu, Ni and thus helpful in the case of Cupro-nickel-jacketed bullet.
2. Utilized for determining the bullet entry and exit holes in case of fully jacketed gilding metal (Cu/Zn) and cupro-nickel (Cu/Ni) bullets.
1. Drawback with the color test is its applicability to detect nitrites only and not for GSR.
2 Another disadvantage is in presence of blood false negative result can be obtained.
Marshall test (Forensic ballistics, Chemical analysis of gunshot residues (GSR), n.d.) Nitrites Purple spots 1.Advantage of the chemical is that it mainly performed to detect the propellant particles in range of firing estimations 1. The test is specific for nitrites and not for GSR
Tewari test (Forensic ballistics, Chemical analysis of gunshot residues (GSR), n.d.) Nitrites Yellow spot 1. Advantage of this test is that it is mainly used for determining range of firing estimations by visualization of propellant particles. 1.Performed specifically for nitrites and not for GSR