Forensic Discrimination of White Architectural Paints Via Atr Ft-Ir Spectroscopy and Chemometrics

The present work entailed the comparative examination and discrimination of white architectural paint samples of different brands/manufacturers. The analysis of these evidence can facilitate to exhibit a linkage between the victim, and the crime scene and ergo assist in the reconstruction of crime scene. Architectural paint traces have evidential value especially in case of burglary, act of vandalism, property crimes etc. In the present study, total 35 samples of white paint with distinct brands were purchased and analysed using ATR FT-IR spectroscopy and multivariate analytical tools. The use of visual analysis of FTIR spectral data resulted in 15 undifferentiated/indistinguishable sample pairs with discrimination power of 97.47%. Adding PCA and PLS-DA in concert with visual analysis of FTIR spectra resulted in 99.4% (3 sample pairs undifferentiated) and 100% of discrimination power, respectively. At the conclusion, samples of each brand were completely differentiated using ATR FT-IR spectra subjected with PLS-DA model. To assess the impact of different substrates on the examination of paint chips, simulated samples were produced on different substrates and the obtained results from substrates study have been summarized. The ATR-FTIR spectroscopy therefore suggests an objective and rapid approach for the discrimination of white architectural paints for forensic purposes.