Rapid and nondestructive analysis of lipstick on different substrates using ATR‐FTIR spectroscopy and chemometrics

Abstract

Lipstick can be an important piece of evidence in crimes like murders, rapes, and suicides. Due to its prevalence, it can be an important corroborative evidence in crime reconstruction. The analysis of such evidence can provide an evidentiary link between the suspect, the victim, object, or the crime scene. We report the use of nondestructive ATR‐FTIR spectroscopy combined with chemometrics for the classification of 10 brands of lipsticks with nine samples each. Chemometric method of partial least square‐discriminant analysis (PLS‐DA) has been employed to interpret the data and classify the samples into their respective classes. The PLS‐DA model provides an AUC figure above 0.99 in all brands except one; for which it is slightly less at 0.94. We have also tested the traces of these lipstick samples on different substrates treating them as unknowns in the already trained PLS‐DA model. 100% of the samples on nine substrates viz. a cotton, nylon, plastic, dry tissue, denim (blue jeans), wet tissue, nitrile gloves, white paper, and polyester were correctly attributed to their source brand. In conclusion, the results suggest that ATR‐FTIR combined with the chemometrics is a rapid, nondestructive, and accurate method for the discrimination and source attribution of lipstick. This study has potential for use in actual forensic casework conditions.

A comprehensive ATR‐FTIR spectroscopic analysis for the identification and differentiation of lip balms

“…The peak at 2850 cm −1 may be attributed to C–H symmetrical stretching. Peaks at the wavenumber of 1605 cm −1 could be due to NH 2 + deformation or C=C stretching vibration [18]. The peak at 1513 cm −1 may indicate the presence of NH deformation or symmetric NH 3 + deformation or C=C stretching vibration [18].…”

“…Peaks at the wavenumber of 1605 cm −1 could be due to NH 2 + deformation or C=C stretching vibration [18]. The peak at 1513 cm −1 may indicate the presence of NH deformation or symmetric NH 3 + deformation or C=C stretching vibration [18]. The peaks at 1461 and 1303 cm −1 are associated with CH 2 asymmetrical scissoring, and C–O stretching, respectively.…”

“…Khei et al [18] analyzed 90 red lipsticks on various substrates by using ATR‐FTIR spectroscopy and chemometrics. The lipsticks were applied to different substrates including blue denim, dry tissue paper, wet tissue paper, plastic, polyester, cotton, nylon, white paper, and nitrile gloves.…”

Delignification and characterization of Tule (Typha Dominguensis) for its potential use in the production of green concrete.

“…The opposite case occurs in the bands in 1170 cm -1 and 1035 cm -1 , where they were more pronounced, indicating an enrichment of cellulose, associated to the contact time for the reactions to take place. On the other hand, a band was formed at 875 cm -1 which is not seen in the untreated Tule, associated to the frequency of the C-1 group or ring frequency, characteristic of the β-glycosidic bonds of the cellulose [8,9,11]. The changes in the bands are associated with a change in the crystalline structure of cellulose.…”

Forensic examination of lipsticks as trace evidence under different environmental conditions

“…In a possible case, this will help the suspect to be associated with the crime scene in a temporal sense. Ka Khei et al [30] have studied the effect of substrate type for discrimination of lipstick samples by using ATR-FTIR. They used various substrates such as wet tissue, nitrile gloves, white paper, and polyester with 10 brands of lipsticks.…”