EDS Data for Duct Tape Adhesives and Tape Edge Specimens
Description
These are datasets of SEM/EDS results obtained in the research project, "Analysis of Small Particles Adhering to the Edges of Duct Tape as a Means to Make Associations in a Way that is Independent of Manufactured Characteristics." The project was supported in part by Award No. 2020-MU-CX-0018 awarded by the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice. The opinions, findings, and conclusions or recommendations expressed are those of the authors and do not necessarily reflect those of the Department of Justice. The data were collected to help determine if very small particles (VSP), acquired post-manufacture and trapped in the adhesive along the edges of duct tape rolls, can discriminate among tape segments from different rolls and provide a quantitative association between segments from the same roll. The datasets have comma separated values files (.csv) that contain data in fields generated by Thermo Fisher Scientific Explorer 4 Analyzer SEM-EDS system using the Automated Feature Analysis (AFA) program within the Thermo Fisher Scientific Corporation Perception 5 software. Analysis is performed under low vacuum conditions (0.075 torr) utilizing a 20.0 kV accelerating voltage, backscatter electron detector (BSED), working distance of approximately 9.5 mm, a spot size of approximately 56% and a magnification of 1,200X. EDS results are based on analysis of x-rays attributable to any of the 18 elements Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn. EDS Copper and Aluminum calibration checks are performed before each analytical run and during the run at the beginning of each specimen. Procedures described below resulted in 9 specimens for each of 30 duct tape rolls: 3 Adhesive Filler Particle specimens (3 stubs prepared from one adhesive swabbing) and 6 Tape Edge Particle specimens (left and right sides of each of the three tape Segments). 32 process control specimens were also collected (one for each Roll during its sampling process, plus two additional specimens for make-up samplings of a fourth Segment). Adhesive specimens for Roll 103, for example, are designated as 103AFA, 103AFB and 103AFC. Left and Right sides of Segment 2 of Roll 103 are designated, for example, as 1032L and 1032R. The Process Control Particle specimens applicable to the sampling of the 3 Segments from Roll 103 is designated, for example, as 103FC. Process Control Specimen S41FC is applicable to Tape Edge Particle Specimens 1164L, 1164R, 1284L, 1284R, 1324L and 1324R, whereas Process Control Specimen S42FC is applicable to Tape Edge Particle Specimens 1114L and 1114R. The spreadsheets contain data on up to 5000 particles for analytical runs of up to 4 hours. For each particle there are entries under column headings as described in the attached file: Column Headings in .csv Files of Particle Datasets.
Files
Steps to reproduce
Partially used silver-colored duct tape rolls, appearing neither new nor heavily used, were collected by research staff from residences within Fairfax County, Virginia. Three successively sampled circumference-length segments were mounted on a clean glass pane. Adhesive filler particles were sampled by swabbing the adhesive (clean room swabs moistened with xylene) from a central portion of the tape (away from tape edges). Tape edge particles were sampled separately from each edge of each segment by applying a bead of a 10% solution of ethyl cellulose in ethanol along the tape edges (as well as a process control bead along the glass) and allowing to solution to dry to a film (2-3 hours). Films were removed using tweezers, dissolved in xylene and the particles washed successively (dilution, mixing, centrifuge) in xylene (to remove soluble adhesive components) and ethanol (to remove xylene). The particle pellet resulting from ethanol washing was re-suspended and filtered through a plastic cell strainers (70 µm pluriSelect) designed for biomedical research. This allowed separation and recovery of fibers and larger trace evidence particles (necessary for integration of the method with existing forensic tape examination procedures). The finer particles passed through the strainer and remained suspended in ethanol. The swabs containing the adhesive from the center of the tape were extracted with xylene. The resulting particle suspensions were washed as described above. Particles were recovered by re-suspension in ethanol and drop wise filtration onto 13 mm/0.4 µm polycarbonate filters and mounting filters onto aluminum SEM stubs using double-sided carbon tape. Methods of SEM/EDS analysis were utilized as previously described in Stoney, D.A., Neumann, C. and Stoney, P.L., Discrimination and Classification among Common Items of Evidence using Particle Combination Profiles, Forensic Science International, Vol 289, pp. 92-107, 2018.