Forensic evaluation and comparison of Indian automobile paint chips using FTIR

Abstract

Identification of trace evidence is one of the most challenging aspects, especially in criminal and road accident investigations, where automobile paint chips may acquit as substantial evidence. In a hit and run case, the trace evidence of automobile paint can be found from the victim as well as from the crime scene by following Principle of Exchange. This study undertaken to assess the comparison of Indian automobile paint chips wherein distinguishing patterns of solubility and profiling of functional groups using FTIR can be done. The present study carried out on 40 samples of Indian automobiles of 2 different companies (Mahindra and Mahindra and Ashok Leyland). The solubility test results have shown that all the paint samples of both the automobile companies gave reactions to different chemical solvents. Out of five different chemical solvents, almost all the samples got solubilised in sulphuric acid with various observations and gave the least reaction in Acetone. The attenuated total reflectance infrared spectroscopy gave effective results to characterise the clear coats from a collection of automotive paint samples representing 10 vehicles. The results shown that Urethane present in almost all the paint samples but amines and hydroxyl group was prominent in the samples of Mahindra and Ashok Leyland respectively with some other resin components. In this study, a database has been created based on solubility and FTIR analysis.