Elemental analysis and characterization of electrical tape backings by LA-ICP-MS

- A novel LA-ICP-MS method was evaluated for the chemical characterization and comparison of electrical tape backings.
- LA-ICP-MS provided improved discrimination (93.9%) when compared with SEM-EDS (87.3%).
- LA-ICP-MS represents a quick, sensitive, and selective method for the elemental analysis of tape evidence.
- The elemental menu for the analysis of tapes increased to 29 elements by using LA-ICP-MS.
- The numerical nature of the data generated is amenable for the creation of a searchable database.

Adhesive tapes are commonly found as physical evidence in cases involving violent crimes and national security threats. This research evaluated the utility of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) for the characterization of chemical signatures of electrical tapes for forensic comparison and provenance purposes. The backings of 90 black electrical tapes, previously characterized by microscopical examination, Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR) and Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS), were analyzed by LA-ICP-MS to evaluate the ability of the technique to discriminate samples originating from different sources and to associate pieces of tapes originating from the same roll. The results showed that LA-ICP-MS is a useful tool that complements current protocols for the organic and inorganic characterization and comparison of electrical tapes and results in improved discrimination and superior characterization. The developed LA-ICP-MS method alone provided 94% correct discrimination of the tapes known to originate from different rolls and 100% correct association of the tapes known to originate from the same roll. Moreover, LA-ICP-MS captured a large amount of compositional information, as the use of elemental profiles alone provide similar discrimination and classification capabilities as all the conventional methods together. The analytical sensitivity of LA-ICP-MS provides a means for the classification of tapes to support investigations as well as the potential for database searching capabilities in the future.

107