Development of new screening reagent, pattern distribution and chemometric application of gunshot residue (GSR) as evidence recovery using fourier transform infrared (FTIR) technique / Siti Nurhazlin Jaluddin

The innovation of chemographic reagent, Rapid Griess Test (RGT) was successfully developed as a rapid and portable screening test kit in detecting GSR at crime scenes. There different chemicals consist of amino group namely, 1,4-phenylenediamine, 1,8- napthalenediamine and 3-aminophenol were tested as substitution of alpha-naphtol in Modified Griess Test (MGT). It was proven that 3-aminophenol has highest efficiency as chemographic reagent. This chemical reagent formed a colour solution upon reacting with nitrite (NO2 - ). Furthermore, the effectiveness of 3-aminophenol as a substitution of alpha-naphthol in RGT prevented the addition of acid and heat for the reaction to occur. In order to determine the pattern distribution and particles dispersion of GSR, the shooting test was performed. The findings showed various firearms produced different pattern distributions and particles dispersion at a closed shooting distance. Specifically, the revolver produced larger soot of GSR pattern distribution at 3 cm of shooting distance compared to the pistol. However, pistol produced more particles dispersion at target materials as compared to the revolver. The factors that affect the various size of soot and particles dispersion is including the barrel length, internal pressure of firearms and the weight of propellants. In the meantime, the morphological structure and chemical composition of GSR from different brands of ammunition were analysed using Scanning Electron Microscope (SEM) and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), respectively. The findings revealed that each ammunition consists of unique characteristics with the propellant’s shape determined by its chemical composition as well as the manufacture. Furthermore, the spherical or round shape of the propellant consists of a single-base propellant and is made up of nitrocellulose and nitro-glycerine. On the other hand, the thin flake propellant consists of a double-base propellant and its components include nitrocellulose, nitro-glycerine and other mixtures. The ATR-FTIR spectrum showed that all the samples consist of main peaks of nitrocellulose, but the percentage transmission of each ammunition was different. This is because the chemical composition of ammunition is different within the manufacture. Due to the huge and complex data set of the ATR-FTIR, chemometric analysis was implemented in the last part of the analysis. Principal Components Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used as a technique of unsupervised chemometric. From PCA analysis, propellant and GSR can be differentiated and grouped according to the types of calibres and brands of ammunition.