These methods are routinely employed in the analysis of paint traces. In this aspect, various techniques such as optical microscopic analysis, scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDX), micro-spectrometry in the ultraviolet (UV) and visible (vis) spectral ranges, pyrolysis gas chromatography-mass spectrometry (GC–MS), micro-X-ray fluorescence (μ-XRF), and so forth, are used for the determination of its chemical composition. What benefits did you anticipate by using ATR-FT-IR spectroscopy over other analytical techniques for your intended analysis? Generally, forensic examination of paint samples includes a comparison of their chemical content. ATR FT-IR spectroscopy, in combination with chemometric tools, yielded valuable results leading to a high degree of discrimination between samples. Henceforth, the non-destructive nature of this method inspired us to move ahead with the analysis of various trace evidence such as spray paints. Therefore, following ATR-FT-IR analysis, samples can be preserved and further analyzed using other analytical methods, if needed. The technique used in this present work is completely non-destructive, rapid, reliable, and eco-friendly in nature. The traditional methods are destructive to the sample which makes the preservation and further analysis of sample not possible. In forensic casework conditions, the samples are often encountered in only trace levels thus, the trace amount of available sample make their analysis very difficult. However, these marks can sometimes be the only available valued evidence deserving a precise analytical method for the identification and for discrimination purposes. Additionally, in many criminal attempts, criminals leave any kind of messages or signs using spray paint at the scene of the crime. The most obvious cases are vandalism and graffiti where spray paints could be utilized to destroy or blot different types of objects. What inspired you to research the ATR-FT-IR method for the purpose of your analysis? These days, spray paints are often used in criminal offenses. Singh spoke to Spectroscopy about the findings, and the paper that resulted from their efforts (1). Rajinder Singh and his colleagues in the Department of Forensic Science at Punjabi University (Punjab, India) have used attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy for nondestructive analysis of 20 red spray paints of different manufacturers, which could possibly be encountered at a crime scene, particularly in case of vandalism. Spray paint is often used by vandals for creating graffiti, as well as for criminals to leave signs, messages, and blots to conceal the left traces at the scene of their efforts.

Spectra paint