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Rapid and nondestructive analysis of lipstick on different substrates using ATR-FTIR spectroscopy and chemometrics |
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| Authors: | Lim Ka Khei BSc Rajesh Verma PhD Eva Lee Yin Tan MSc Kah Hin Low PhD Dzulkiflee Ismail PhD Muhammad Naeim Mohamad Asri PhD |
| Institution: | 1. Forensic Science Program, Department of Diagnostic and Allied Health Science, Faculty of Health and Life Science (FHLS), Management and Science University, Selangor, Shah Alam, Malaysia
School of Graduate Studies, Management & Science University, Selangor, Shah Alam, Malaysia;2. Regional Forensic Science Laboratory, Himachal Pradesh, Mandi, India;3. Forensic Science Program, Department of Diagnostic and Allied Health Science, Faculty of Health and Life Science (FHLS), Management and Science University, Selangor, Shah Alam, Malaysia School of Graduate Studies, Management & Science University, Selangor, Shah Alam, Malaysia Global Affairs, Management & Science University, Selangor, Shah Alam, Malaysia;4. Department of Chemistry, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia;5. Forensic Science Program, School of Health Sciences, Universiti Sains Malaysia, Health Campus, Kelantan, Kubang Kerian, Malaysia;6. Department of Forensic Medicine, Faculty of Medicine, Manipal University College Malaysia, Melaka, Malaysia |
| 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. |
| Keywords: | ATR-FTIR spectroscopy chemometrics lipstick partial least square-discriminant analysis |