Spectroscopic and chemometric evaluation of cling films used for wrapping of foodstuff and illicit drugs Vishal Sharma ⁎, Dova Nani, Raj Kumar Institute of Forensic Science & Criminology, Panjab University, Chandigarh 160014, India abstract article info Article history: Received 21 May 2018 Received in revised form 20 August 2018 Accepted 26 August 2018 Available online 29 August 2018 Thin films of various polymers are currently used for wrapping various food products and illicit drugs worldwide. In thin films, polyvinyl chloride is the third most widely used polymer after the polyethylene and polypropylene. These films usually contain harmful plasticizers such as adipates, phthalates, and citrates along with other addi- tives. Plasticizers adversely affect the human health and therefore, their migration in foodstuff must be moni- tored carefully. By considering all thesefacts, this study summarizes the utilities of non-destructive ATR-FTIR spectroscopy in the identification of base polymer as well as plasticizers in various cling films and application of multivariate analysis in the identification and classification of the cling films to their respective groups. In the present research, a considerable transfer of plasticizers from the wrapping material is observed. A spectral li- brary is developed for all 22 cling film samples for further comparison of the unknown sample. The obtained re- sults are promising, especially for classification purposes. The multivariate method significantly provides 100% of cross-validation classification along with 99.13% discrimination. In this study, we have developed a method to compare or link a cling film which somebody uses and found that there is a transfer of plasticizers and other ad- ditives into the food and if the manufacturing company disown that this specific cling film does not belong to our company. In such type of cases, this method could link the suspected cling film to their manufacturers with pre- cision and accurateness. The chronic effect of plasticizers on human health can also be linked to the type of cling film the accused was using consistently. © 2018 Elsevier B.V. All rights reserved. Keywords: Cling films Plasticizers ATR-FTIR Multivariate analysis Classification Chemometrics 1. Introduction The cling films are usually the plastic films used for packing of food materials to keep them fresh for longer period of time. These films are sold in the form of rolls for wrapping the food materials worldwide. The base polymer in cling film is either polyvinyl chloride (PVC) or low-density polyethylene (LDPE). Copolymerization of LDPE with vinyl acetic acid derivatized to ethylene vinyl acetic acid (EVA) which is responsible to give required characteristics to the cling film e.g. pro- tection from oxidation and inertness to the impacts of ultraviolet and visible light [1]. Further, various additives such as dyes, pigments, stabi- lizers, plasticizers such as adipates, citrates, phthalates [2,3] and antiox- idants are incorporated in cling films to get desirable properties [4]. Plasticizers are the compounds generally incorporated in numerous polymer-based products. These compounds generally transferred when come in contact with solids and liquid materials because of their low molecular weight. The lipophilic nature of these plasticizers supports their migration into fat and oil components of food products [5–8]. These types of migration have been studied by the researchers [9]. However, the research in this area still requires much attention world- wide [3,10,11] because of the fact that the consumption of the plasti- cizers adversely affects the human reproductive, respiratory, and endocrine system. It might also cause skin diseases as well [12–14]. In 1999, the toxicological studies lead to the ban on the addition of phthalates in food packing materials [15] in European countries. How- ever, these materials are still used in India for wrapping purposes. Therefore, the effective methods to detect these additives are needed for their monitoring and identification effectively in various cling film based products. The polymers are further utilized in many applications like packing of illegal drugs [16], developing explosive devices, and shielding of elec- tric wires, etc. The polymers associated with such trafficking of drugs etc. are usually present on the substrate which can be used as evidence. Their examination can establish a correlation between a suspect and his modus operandi [17] which will help the investigating agencies. 1.1. Examination of Cling Films The characterization of cling films used for packaging of food prod- ucts is very important. There are numerous dissimilarities exist in the cling films manufactured by the same company with the different Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 206 (2019) 558–568 ⁎ Corresponding author. E-mail address: sharmavishal05@gmail.com (V. Sharma). https://doi.org/10.1016/j.saa.2018.08.052 1386-1425/© 2018 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa