Preliminary Evaluation of Gunshot Residue (GSR) Using 3-Aminophenol as a Substitute in Modified Griess Test

In forensic ballistics, gunshot residue (GSR) particles can be detected using screening or presumptive tests which are mainly focused on the chromophoric reaction. Most tests serve as an initial indication for a forensic investigator at the crime scene before instrumental analysis for definitive identification. The screening methods are known to be convenient, have fast analysis, and minimal preparation. In GSR analysis, the well-known method of detecting GSR known as the Modified Griess Test (MGT) requires acid and heat for the reaction. Therefore, this study demonstrated a new and rapid screening test named the Rapid Griess Test (RGT) for the detection of GSR. This study intends to improve the functionality of previous screening reagents in determining nitrite (NO2–), the composition present after shooting activity. To do this, chemical reagents with an amino group, 3-aminophenol, were substituted with alpha-naphthol. The experiment showed that the reactions were positive color changes using standard NO2– and real GSR samples. The diazotization reactions involving sulfanilic acid and 3-aminophenol produced azo dyes that changed the solution from colorless to orange in the presence of NO2–. The RGT reagent will make it possible to avoid using heat and the addition of acetic acids in a sample to form chromophoric reactions. Moreover, the colorimetric method using Video Spectral Comparator (VSC) showed that RGT had higher intensity of the orange color when compared to MGT.

Determination of Temik Residues in Raw Fruits and Vegetables

Temik, 2-methyl-2-(methylthio) propionaldehyde O-(methylcarbamoyl)oxime, is a systemic pesticide effective both by topical application to the plant and by systemic translocation from treated soil. The method developed for residues of Temik in crops is based on extraction of the crops with chloroform, followed by cleanup involving both coagulation and liquid partitioning techniques. The analysis involves both base- and acid-catalyzed hydrolysis to liberate hydroxylamine, which is then oxidized by iodine to nitrous acid; the latter is determined by diazotization (a modification of the Griess test for nitrites). The method is sensitive to about 0.03 ppm; average recovery from 8 crops is 96.3 ± 3.2%. Other current commercial pesticides do not interfere in the analysis.