Forensic Fiber Analysis by Thermal Desorption/Pyrolysis-Direct Analysis in Real Time-Mass Spectrometry

Abstract

The thermal desorption/pyrolysis-direct analysis in real time-mass spectrometry (TD/Py-DART-MS) method was developed for the analysis of fibers in this study. The fiber samples were pyrolyzed with a temperature gradient and the pyrolysis products were determined by DART-MS. The pyrogram from the TD/Py-DART-MS fiber analysis was found to be associated with the physical properties such as the melting points. At the same time, the TD/Py-DART-MS allows the analyst to obtain the chemical information such as polymeric backbone structures and dyes on the fiber. The pyrolysis profiles of common polymeric fibers in textile materials such as cotton, cellulose triacetate (CT), poly­(caprolactam) (nylon-6), poly­(hexamethylene adipamide) (nylon-6/6), poly­(acrylonitrile) (PAN), poly­(ethylene terephthalate) (PET), poly­(butylene terephthalate) (PBT), poly­(propylene) (PP), and polytrimethylene terephthalate (PTT) and their respective characteristic mass spectra were reported in this study. The fibers from 40 commercial textile samples were analyzed by the TD/Py-DART-MS method, and the statistical methods including principal component analysis (PCA) and Pearson product moment correlation (PPMC) were applied to classify and associate the fibers based on their mass spectral data. The strong correlation between the reference fiber mass spectral profiles and tested fiber mass spectral profiles was observed by using the PPMC method, and the identification accuracy was 97.5%. When combined, the mass spectral and pyrogram data, the types of fibers including the blended fibers were identified effectively. The TD/Py-DART-MS method also demonstrated the promising capability for the identification of dyes on fibers. Overall, the TD/Py-DART-MS method requires small sample size and minimal sample preparation but offers reproducible and multidimensional information for the fiber evidence rapidly (i.e., ∼6.7 min). Since the proposed method is simple to perform and the data are easy to interpret, this approach may significantly contribute to the fiber identification and comparison procedures in forensic settings with high sample throughput potential.

Characterization of synthetic dyes for environmental and forensic assessments: A chromatography and mass spectrometry approach

“…Textile fibers from clothing, home furnishings, and industrial fabric (such as tarps, ropes, and upholstery) can be one of the most abundant sources of forensic evidence at almost any crime scene. Typically, these fibers have some sort of colorant attached to them, which can make them an important piece of evidence used for the positive identification of a suspect [6–8]. The same concept can be applied to plastics, food, and painted objects (tool transfer residue or automobile chips/residues), which also contain colorants, either in the form of a dye or, more commonly, a pigment [9,10].…”

“…In the case of disperse dyes, a common practice for analysis and identification is the use of LC or LC‐MS with the sample extracted from the fiber [17,77,79,100,101]; however, several studies have shown that dyes can be identified with direct ionization methods [7,74]. DART uses a stream of heated metastable gas to vaporize and ionize analytes, sending them directly into the mass spectrometer for analysis [7,85]. This method generates real‐time mass spectra of a sample simply by holding the sample in front of the source, whether it is a pharmaceutical tablet, a dollar bill, or a textile fiber.…”

Strategy for Sustainable and Green Chromatographic Separation Science: Innovation, Technology and Application

“…Nowadays, PHWE has become a popular green extraction technique for the extraction of various types of compounds from different types of environmental, food and plant materials. It has also been used for the extraction and removal of organic compounds from foodstuff and soils to ensure food safety and environmental monitoring [52]. PHWE is an alternative to organic solvent extraction which uses pressurized water to extract compounds at high temperature and controlled pressure.…”

“…There are some major advantages of PHWE since it reduces the consumption of organic solvents in extraction, water is available everywhere and is non-toxic, easily disposable and recyclable with minimum environmental difficulties. It is a low-cost method that is efficient in extracting less-polar organic compounds from a variety of matrices [52,57,58].…”

Forensic Analysis of Polymeric Carpet Fibers Using Direct Analysis in Real Time Coupled to an AccuTOF™ Mass Spectrometer

“…Nylons, also referred to as polyamides, are a group of synthetic polymers that are used to manufacture rope, fabric, carpet fibers, and more [ 1 ] Various kinds of nylons are differentiated based on their synthesis [ 2 ]. A few examples of the various nylons include nylons 6, 6/6, 11, etc.…”