Differentiation of locally manufactured Kajal by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy supported by chemometric analysis.

Abstract

Kajal, also known as Kohl (Arabic name) a cosmetic, is used for the beautificationof eyes and face as a whole. It can serve as an important corroborative evidence in various crimes against women and can also be used as a writing instrument to write the anonymous letters, threatening notes, suicide letters on a variety of substrates such as cotton cloth, tissue paper, tissue wipes, skin etc. 40 Kajal samples from 33 different brands were collected and analyzed using Attenuated Total Reflectance Fourier Transform Infrared (ATR FT-IR) Spectroscopy with advance statistical and computational tools. The present research investigated the application of this technique for the differentiation of locally manufactured Kajal based on the differences in the peak patterns, frequencies, and strengths of peak exhibited within the fingerprint region. The blind test was conducted with four unknown samples which were pretended to be unknown to the analyst and it was observed that all the unknown samples were predicted correctly with their respective classes. Effect of substrates and ageing were also studied under similar set of experimental conditions. This technique has been proven to be of high significance with complete non-destructive nature requiring minimal or no sample preparation and high repeatability.