The Comparison and Matching of Low Density Polyethylene Plastic Bags by Infrared Spectroscopy

Abstract

Low density polyethylene (LDPE) is by far the most common polymer film material. Bags and pouches made from LDPE are readily available and are being used as packaging by peddlers of illegal drugs and by other criminals. It is therefore important that an investigator have ways of comparing LDPE bags used in the commission of a crime with bags belonging to a suspect.

A quantitative assessment of the chemical variation in food grade polyethylene cling film, a common wrapping material for illicit drugs, using attenuated total reflection-Fourier transform infrared spectroscopy

“…This is consistent with the findings of another study which concluded that LDPE bags had the same IR spectra between 4000 and 1800 cm À1 but displayed differences between 1600 and 400 cm À1 . 6 To test the hypothesis that the spectral region between 1560 and 1200 cm À1 could provide discrimination between LDPE cling film samples, high resolution IR spectra were acquired for one square of the five originally analysed. As the full scan IR spectra had shown that within-sample chemical variation was reasonably low, it was assumed that analysis of one square would be representative of the initial five, and thus the entire roll of cling film.…”

“…The analysis of polymeric materials is a frequent examination in forensic investigations. 1 Some examples reported in the literature include fibres, 2,3 latex gloves, 4,5 plastic bags, [6][7][8][9][10][11][12] packaging tapes, [13][14][15][16] cellophane, 17 paper 18,19 and cardboard. 20 A polymeric substance frequently encountered as a wrapping material for illicit drugs is cling film due to its ready availability and low cost.…”