Chemical fingerprinting of adhesive tapes by GCMS detection of petroleum hydrocarbon products

Abstract

Pressure-sensitive adhesive tapes often represent key evidence of crimes such as assault, rape or homicide; thus, the development of analytical techniques able to contribute to a detailed characterization of these materials is of forensic importance. The gas chromatography-massspectrometry (GCMS) analysis of the solvent extractable fractions of a suite of electrical and gaffer adhesive tapes spanning a range of colors and manufacturers identified a number of petroleum-derived hydrocarbons. Molecular and isotopic analyses of hydrocarbon constituents of complex materialshave found wide analytical utility including the forensic investigation of oil spills and arson. Here, we investigate the utility of these techniques for characterizing the hydrocarbon composition of pressure-sensitive adhesive tapes for forensic correlation purposes. Subtle distinction of tape sampleswas evident in the GCMS distribution of several hydrocarbon groups including alkyl-naphthalenes, hopane and sterane biomarkers. Linear discriminant analysis of the abundances of these products provided high level differentiation of tape manufacturer. The distinction of different adhesivetape samples was further extended by measurement of their stable carbon isotopic values. The molecular and isotopic differences of the petroleum content of tapes are consistent with the use of different petroleum materials used in the manufacturing process and demonstrate the benefits of thecombined use of complementary oil hydrocarbon characterization approaches. This study reveals the forensic potential of using established petroleum characterization methods for characterizing materials with a petroleum-derived hydrocarbon element.