Analysis and Discrimination of Electrical Tapes: Part II. Backings*^,†

Abstract

The backings of 90 black electrical tapes were analyzed to evaluate the chemical components of these films, the ability of individual techniques to discriminate samples, and the ability of the techniques combined to distinguish samples. The techniques utilized and their respective discrimination results were stereomicroscopy and physical measurements, to include observation of surface features of the backing, width, and thickness measurements (c. 64%); Fourier transform infrared spectroscopy (FTIR) using a microscope accessory (c. 83%); pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS; c. 81%); and scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS; c. 87%). Ninety-four percent of the backings were discriminated through this combination of analytical methods. Finally, evaluating these results in conjunction with previously published data on the analysis of the adhesives from the same set of electrical tapes provided an overall discrimination of nearly 96%.

Interlaboratory evaluations of the performance of elemental analytical methods for the forensic analysis and comparisons of electrical tapes

“…The physical and microscopic examination of tapes include the description of the texture of the backings, the color of the adhesive, the thickness of the different layers of the tapes, the number of different layers present, and when possible, the examination of potential physical fit between torn edges [1][2][3][4][5][6][7][8]. For most laboratories, visual examination is the first step of the analytical scheme and is usually followed by a supplemental instrumental method of analysis.…”

“…For most laboratories, visual examination is the first step of the analytical scheme and is usually followed by a supplemental instrumental method of analysis. The identification of the organic components of the tapes is usually accomplished by Infrared spectroscopy (IR) and Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC-MS) [5,6,[8][9][10][11][12]. These two methods are almost orthogonal and therefore, when combined, provide improved characterization of the organic constituents and superior discrimination [6].…”

“…The identification of the organic components of the tapes is usually accomplished by Infrared spectroscopy (IR) and Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC-MS) [5,6,[8][9][10][11][12]. These two methods are almost orthogonal and therefore, when combined, provide improved characterization of the organic constituents and superior discrimination [6]. The inorganic analysis of tapes is commonly conducted by Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) and X-ray Fluorescence (XRF) [1,2,[4][5][6]8].…”

“…These two methods are almost orthogonal and therefore, when combined, provide improved characterization of the organic constituents and superior discrimination [6]. The inorganic analysis of tapes is commonly conducted by Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) and X-ray Fluorescence (XRF) [1,2,[4][5][6]8]. These techniques have proved useful in characterizing the elemental composition of tape samples.…”

Forensic examination of plastic drinking straws based on their physical characteristics and manufacturing marks

“…To the best of our knowledge, while the forensic examinations of other drug packaging materialssuch as plastic bags [11][12][13][14][15][16][17], packaging films [17,18], newspapers [19,20], and adhesive tapes [21][22][23][24][25][26][27]had been reported, corresponding studies of drinking straws have not been done. We thus compared the physical characteristics and manufacturing marks of drinking straws from various commercial sources available in Singapore to evaluate their discriminatory values, as well as to gain a better understanding of typical internal variations that might be encountered.…”