Identification of Carbonates as Additives in Pressure‐Sensitive Adhesive Tape Substrate with Fourier Transform Infrared Spectroscopy (FTIR) and Its Application in Three Explosive Cases

Abstract: Pressure‐sensitive tape is often used to bind explosive devices. It can become important trace evidence in many cases. Three types of calcium carbonate (heavy, light, and active CaCO₃), which were widely used as additives in pressure‐sensitive tape substrate, were analyzed with Fourier transform infrared spectroscopy (FTIR) in this study. A Spectrum GX 2000 system with a diamond anvil cell and a deuterated triglycine sulfate detector was employed for IR observation. Background was subtracted for every measurement, and triplicate tests were performed. Differences in positions of main peaks and the corresponding functional groups were investigated. Heavy CaCO₃ could be identified from the two absorptions near 873 and 855/cm, while light CaCO₃ only has one peak near 873/cm because of the low content of aragonite. Active CaCO₃ could be identified from the absorptions in the 2800–2900/cm region because of the existence of organic compounds. Tiny but indicative changes in the 878–853/cm region were found in the spectra of CaCO₃ with different content of aragonite and calcite. CaCO₃ in pressure‐sensitive tape, which cannot be differentiated by scanning electron microscope/energy dispersive X‐ray spectrometer and thermal analysis, can be easily identified using FTIR. The findings were successfully applied to three specific explosive cases and would be helpful in finding the possible source of explosive devices in future cases.     

The Use of Adhesive Tape for Recovery of DNA from Crime Scene Items

Abstract: The selection of the appropriate method of collection of biological material from crime scene items can be crucial to obtaining a DNA profile. The three techniques commonly used for sampling items are: cutting, swabbing, and taping. The tape sampling technique offers an advantage, in that it enables the collection of a potentially highly informative source of DNA, shed epithelial cells, from selected areas on crime scene items (the inside fingers of a glove, for instance). Furthermore, surface collection of biological material by taping reduces co‐sampling of known PCR inhibitors such as clothing dyes. The correct choice of tape for crime scene item sampling is important. Not all tapes are suitable for biological trace evidence collection as well as DNA extraction. We report on one tape that met both these criteria. Three different cases are presented which demonstrate the usefulness of adhesive tape sampling of crime items. Finally, the advantages of the tape collection technique are discussed and guidelines for preferred areas of tape sampling on various casework items are presented.     

枪击案件中射击残留物提取方法的探讨

目的结合现场勘查提取和实验研究,探讨了几种提取射击残留物的不同方法。方法采用富集浓缩、颗粒收集等方法。结果运用上述方法提取了附着在玻璃、汽车、塑料和织物上弹孔周围的射击残留物。结论收到良好的效果,大大提高了射击残留物提取率和检出率。     

Combined DNA Typing and Protein Identification from Unfired Brass Cartridges,,,

Biological evidence analysis from contact traces is adversely affected by low quantity and quality of DNA. Proteins in these samples contain potentially individualizing information and may be particularly important for difficult surfaces such as brass, where DNA may yield incomplete profiles. In this study, touched unfired brass cartridges were sampled using dry tape or wet swabs and analyzed by separating DNA and protein from the same collected material, thus producing both genomic and proteomic information. DNA recovery was similar for both collection methods, with tape yielding an average of 1.36 ± 1.87 ng and swabs, 1.34 ± 3.04 ng. Analysis by mass spectrometry identified 95 proteins, with the two collection methods showing no significant difference (p = 0.76) in the average number of collected proteins: 44.5 ± 10.9, (tape) versus 47.9 ± 20.4 (swabs). Proteins can be collected from fingerprints at levels necessary to provide identifying information, thus expanding information obtained from challenging evidence.     

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

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-mass spectrometry (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 materials have 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 samples was 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 adhesive tape 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 the combined 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.     

A validation study for duct tape end matches

Fracture matches are considered to be the strongest association achievable in forensic examinations of glass, metal, wood, plastic, paint, tape, and other trace evidence. Despite being fairly routine examinations, few publications exist to support their admissibility in court. This study was designed, using duct tape as the fractured medium, to determine the validity and error rate associated with conducting end match (fracture match) examinations on this material. Five test designs, which varied either the source roll of tape or manner of separation (torn or cut) from the roll, were administered to four analysts with instructions to examine the assigned test sets for end matches. If an end match was not identified by the initial analyst, the entire test set was independently evaluated by the remaining three analysts. Results indicated that while tape grade did not hinder end match identification, the manner of separation could affect results.     

透明胶带的厚度检验

目的研究不同品牌透明胶带的区分方法。方法利用测厚仪对35种不同品牌透明胶带的厚度进行检验,并对所得数据进行统计分析。结果 35种品牌透明胶带组成的595组样品对中有458组可以区分,区分率为77.0%。结论厚度检验法能够在一定程度上区分不同品牌的透明胶带,厚度检验结果可与化学成分检验相互佐证,使得鉴定结论更加准确可靠,为法庭科学领域透明胶带物证的区分提供了一种预检验方法。     

碳素墨水显现胶带粘面手印原理与工艺初探

目的：通过实验得出碳素墨水方法显现胶带粘面手印的原理与恰当工艺。方法：用不同方式制作样本,验证显现原理;控制不同条件,优选出恰当的工艺。结果：归纳出碳素墨水方法显现胶带粘面手印的原理及恰当的操作工艺。结论：本研究结果对实际应用有较大参考价值。     

A Novel Solvent-based Method to Separate Duct Tape from Porous Surface for Fingerprint Development

In this study, we have proposed a novel solvent-based method using a specific concentration of 3M™ Novec™ HFE-72DE and 7200 solvents to untangle duct tape from porous article with minimal impact to the quality of latent fingerprint deposited on the sticky-side surface of duct tape. A series of experiments determined that a mixture of 30% HFE-72DE:7200 (v/v) was found to be the most effective to separate various brands of duct tape from different types of porous surface, including office copy paper, newspaper, cardboard, and tissue wipe, which had been stored for up to 30 days before untangling. Further studies also revealed that 30% HFE-72DE:7200 was compatible with three common fingerprint development methods for porous articles, namely ninhydrin, indanedione-zinc, and physical developer. The nonflammability and low toxicity nature of this novel solvent mixture also make it ideal for separating duct tape from porous surface in laboratory or at crime scene.