| Autor: |
Ledergerber TD; Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA. Tatiana.trejos@mail.wvu.edu., Feeney W; National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, MD 20899, USA., Arroyo L; Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA. Tatiana.trejos@mail.wvu.edu.; Department of Forensic and Investigative Science, West Virginia University, Morgantown, WV 26506, USA., Trejos T; Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA. Tatiana.trejos@mail.wvu.edu.; Department of Forensic and Investigative Science, West Virginia University, Morgantown, WV 26506, USA. |
| Abstrakt: |
This study reports the use of direct analysis in real time-mass spectrometry (DART-MS) for the detection of organic gunshot residues (OGSR) in a variety of matrices of interest for forensics, customs, and homeland security. Detection limits ranged from (0.075 to 12) ng, with intra- and inter-day reproducibility below 0.0012% CV. The collection of mass spectra at multiple in-source collision-induced dissociation (is-CID) voltages produced distinctive mass spectral signatures with varying levels of fragmentation and allowed differentiation of isomers. To test method performance, a collection of 330 authentic specimens from various substrates were analyzed - (1) neat smokeless powders, (2) spent cartridge cases, (3) burnt particles removed from clothing via carbon stubs or (4) with tweezers, and hand samples from (5) non-shooters, and (6) shooters. A subset of hand specimens ( n = 80) was further analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for confirmation and comparison. Seven types of ammunition from five manufacturers and two calibers were monitored for OGSR profiles with similar compositions observed for paired sets ( e.g. , unburnt smokeless powder and the respective residues on spent cartridges, clothing, and hands). No false positives were observed across all datasets. A 100% true positive rate (TPR) was observed for all substrates except the shooters' hands. Depending on the ammunition type and classification criteria, the shooters' hands exhibited a TPR ranging from 19% to 73%. The results show that DART-MS is feasible and versatile for fast screening of OGSR across various substrates but may benefit from alternative approaches to improve detection at trace levels. |
