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

Abstract

Polymeric fibers are encountered in numerous forensic circumstances. This study focused on polymeric carpet fibers most encountered at a crime scene, which are nylons, polyesters and olefins. Analysis of the multiple polymer types was done using Direct Analysis in Real Time (DART™) coupled to an Accurate time-of-flight (AccuTOF™) mass spectrometer (MS). A DART gas temperature of 275 °C was determined as optimal. Twelve olefin, polyester, and nylon polymer standards were used for parameter optimization for the carpet fiber analysis. A successful identification and differentiation of all twelve polymer standards was completed using the DART-AccuTOF™. Thirty-two carpet samples of both known and unknown fiber composition were collected and subsequently analyzed. All samples with known fiber compositions were correctly identified by class. All of the remaining carpet samples with no known composition information were correctly identified by confirmation using Fourier-transform infrared spectroscopy (FTIR). The method was also capable of identifying sub-classes of nylon carpet fibers. The results exhibit the capability of DART-AccuTOF™ being applied as an addition to the sequence of tests conducted to analyze carpet fibers in a forensic laboratory.

Interpol review of fibres and textiles 2019-2022

“…Alternatives for fibre identification are mentioned by Liang et al in the use of thermal desorption/pyrolysis-direct analysis in real time-mass spectrometry (TD/Py-DART-MS) for the identification of fibres [ 81 ], Zhou et al in discussing the possibility to identify textile fibres with near-infrared spectroscopy and pattern recognition. [ 82 ] and Zughaibi et al by the use of Direct Analysis in Real Time Coupled (DART) coupled to an accurate time-of-flight (AccuTOF) mass spectrometer (MS) and where they were able to correctly identify 22 carpet samples [ 83 ].…”

Applications of ambient ionization mass spectrometry in 2021: An annual review

“…Finally, DART-MS in particular has been applied to a range of forensically relevant sample types. This technique has been demonstrated in the analysis of sexual lubricants to evaluate storage conditions for sexual assault evidence, 79 the analysis of animal products to battle illegal trading, 80,81 polymeric carpet fibres for material identification 82 and seed-based toxins encountered in cases of poisoning. 83 Gao et al combined REIMS with multivariate analysis to differentiate between leather products sourced from different animals, a method that would be beneficial in leather product testing and authenticity confirmation.…”

The characterization of disperse dyes in polyester fibers using DART mass spectrometry

“…As the name suggests, spectra can be observed in real time and collection can be both continuous and pulsed [ 4 , 6 , 7 ]. The lack of sample preparation required allows for rapid, easy testing that has great potential for use in forensic sciences [ 5 , 8 , 9 , 10 , 11 , 12 , 13 ]. Case and evidence backlogs are a significant problem in forensic laboratories, so high turnover during testing and the potential to test on‐site are both desirable attributes for an analytical method.…”

“…The ability to test materials directly helps to prevent degradation, destruction, or alteration of the original sample, allowing evidence to survive for additional or separate testing and presentation at trial [ 14 , 15 , 16 , 17 ]. In related studies, DART has been used in the analysis of historical colorants, such as pigments from organic sources used in prints and paints from artifacts due to its speed, sensitivity, and lack of sample preparation needed, allowing for conservation of archeological and otherwise significant objects [ 5 , 8 , 9 , 10 , 11 , 12 ].…”