skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Comparison of portable and benchtop GC–MS coupled to capillary microextraction of volatiles (CMV) for the extraction and analysis of ignitable liquid residues
Title: Comparison of portable and benchtop GC–MS coupled to capillary microextraction of volatiles (CMV) for the extraction and analysis of ignitable liquid residues
A novel extraction device, capillary microextraction of volatiles (CMV) was coupled to a TRIDION-9 GC–MS with a needle trap (NTD) and evaluated for the analysis of ignitable liquids fire debris. The performance of the TRIDION-9 was compared to a benchtop GC–MS using CMV. A system detection limit of ~10 ng for each of 20 key ignitable liquid residue (ILR) compounds was determined for the T9 GC–MS. Dynamic headspace sampling of simulated ILRs was performed in closed and open-air systems. Closed system evaluations the CMV/NTD technique resulted in extraction performance similar to the CMV alone; however, ILR analysis on the T9 was impacted by limited chromatographic resolution. Compound identification was possible for 14 out of the 20 selected compounds on the T9 when 1 μL of a 1% standard accelerant mixture (SAM) was sampled, compared to 17 compounds on the benchtop GC–MS for the same mass loading. Open-air sampling with a modified vapor source resulted in the retention of most compounds with as low as 5 min. sampling, and equilibrium concentrations were reached after 10 min. No significant differences were observed between CMV and CMV/NTD sampling suggesting that the combined technique does not suffer from affinity bias. While the potential of the CMV/NTD extraction coupled to a T9 GC–MS for fire debris analysis was limited by the chromatographic resolution of the instrument, this study serves as proof of concept for the CMV’s potential for the extraction of ILRs in combination with portable GC–MS systems.  more » « less
Award ID(s):
1739805
PAR ID:
10166489
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Forensic chemistry
Volume:
19
ISSN:
2468-1709
Page Range / eLocation ID:
100240
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. (, The chemical educator)
    Henry Charlier (Ed.)
    This paper reports an approach that developed instrumental parameters with two different GC-MS instruments. Data from the two devices were combined with principal component analysis (PCA) to analyze genuinely and ignited ignitable liquid residues (ILR). We simulate the field samples by burning seasoned pinewood soaked with each ignitable liquid (IL). Enough unburnt components from an IL remained on the burnt wood. These components were enough to reveal the chromatographic fingerprint of an IL. Most importantly, the chromatographic profile from a pure IL and IL poured onto a wooden substrate and ignited was identical. The chromatographic profiles reported from each instrument for each IL were reproducible to within 3% RSD. The MS data from both GC-MS instruments showed similar m/z peaks from all ILs, indicating similar hydrocarbon(s) and or fragmentation cluster patterns in the ILs studied ingredients. The PCA data showed characteristic differences giving rise to the separation between incendiaries, albeit some were overshadowed by clustering. In some cases, ILs that showed similar components in their mass spectra profile grouped as a class on the PCA display. We demonstrate an approach using direct headspace injection to individualize ILs recovered from crime scenes. Direct headspace injection and GC-MS combined with PCA are shown as promising facile methods for the qualitative determination of specific ILs in real-world arson samples. Initially, our project started as an undergraduate instrumental analysis guided-inquiry (GI) project. Such labs have been reported to enhance student learning and improve students' critical and problem-solving abilities. We plan to incorporate this approach in both an undergraduate instrumental analysis class and a graduate-level analytical chemistry class. 
    more » « less
  2. ; ; ; (, Talanta)
    Determination of olefins in pyrolysis oils from waste plastics and tires is crucial for optimizing the pyrolysis process and especially for the further advanced valorization of these oils in terms of the circular economy. Identifying olefins, even using high-resolution techniques like GC×GC, is challenging without TOF-MS, which allows modification of the ionization step. Currently, the only method for determining olefins in plastic pyrolysis oils is GC-VUV, recently standardized as ASTM D8519. However, TOF-MS and VUV are not affordable instruments for many research teams working on plastics recycling. This paper introduces a simple method for the selective micro-scale adsorption of olefins over AgNO3/SiO2, followed by the GC×GC-FID analysis. Olefins are determined indirectly from the loss of chromatographic area in respective hydrocarbon groups before and after removal. Only 50 μL sample and 15 min of sample separation are needed. Our method was extensively validated and provides a reliable determination of olefin content in a wide range of pyrolysis oils from plastics and tires and their products after mild hydrotreatment. It is affordable to all researchers and industrial companies working on plastics recycling by thermochemical processes as it does not require an MS detector. 
    more » « less
  3. ; ; (, Rapid Communications in Mass Spectrometry)
    RationaleSilicone wristbands have emerged as valuable passive samplers for monitoring of personal exposure to environmental contaminants in the rapidly developing field ofexposomics. Once deployed, silicone wristbands collect and hold a wealth of chemical information that can be interrogated using high‐resolution mass spectrometry (HRMS) to provide a broad coverage of chemical mixtures. MethodsGas chromatography coupled to Orbitrap™ mass spectrometry (GC/Orbitrap™ MS) was used to simultaneously perform suspect screening (using in‐house database) and unknown screening (using vendor databases) of extracts from wristbands worn by volunteers. The goal of this study was to optimize a workflow that allows detection of low levels of priority pollutants, with high reliability. In this regard, a data processing workflow for GC/Orbitrap™ MS was developed using a mixture of 123 environmentally relevant standards consisting of pesticides, flame retardants, organophosphate esters, and polycyclic aromatic hydrocarbons as test compounds. ResultsThe optimized unknown screening workflow using a search index threshold of 750 resulted in positive identification of 70 analytes in validation samples, and a reduction in the number of false positives by over 50%. An average of 26 compounds with high confidence identification, 7 level 1 compounds and 19 level 2 compounds, were observed in worn wristbands. The data were further analyzed via suspect screening and retrospective suspect screening to identify an additional 36 compounds. ConclusionsThis study provides three important findings: (1) a clear evidence of the importance of sample cleanup in addressing complex sample matrices for unknown analysis, (2) a valuable workflow for the identification of unknown contaminants in silicone wristband samplers using electron ionization HRMS data, and (3) a novel application of GC/Orbitrap™ MS for the unknown analysis of organic contaminants that can be used in exposomics studies. 
    more » « less
  4. ; (, Rapid Prototyping Journal)
    Purpose This paper aims to study the mass loss of three-dimensional (3D) printed materials at high temperatures. A preconcentration and analysis technique, static headspace gas chromatography-mass spectrometry (SHS-GC-MS), is demonstrated for the analysis of volatile compounds liberated from fused deposition modeling (FDM) and stereolithography (SLA) 3D printed models under elevated temperatures. Design/methodology/approach A total of seven commercial 3D printing materials were tested using the SHS-GC-MS approach. The printed model mass and mass loss were examined as a function of FDM printing parameters including printcore temperature, model size and printing speed, and the use of SLA postprocessing procedures. A high temperature resin was used to demonstrate that thermal degradation products can be identified when the model is incubated under high temperatures. Findings At higher printing temperatures and larger model sizes, the initial printed model mass increased and showed more significant mass loss after thermal incubation for FDM models. For models produced by SLA, the implementation of a postprocessing procedure reduced the mass loss at elevated temperatures. All FDM models showed severe structural deformation when exposed to high temperatures, while SLA models remained structurally intact. Mass spectra and chromatographic retention times acquired from the high temperature resin facilitated identification of eight compounds (monomers, crosslinkers and several photoinitiators) liberated from the resin. Originality/value The study exploits the high sensitivity of SHS-GC-MS to identify thermal degradation products emitted from 3D printed models under elevated temperatures. The results will aid in choosing appropriate filament/resin materials and printing mechanisms for applications that require elevated temperatures. 
    more » « less
  5. ; ; ; ; ; (, AWWA Water Science)
    Abstract Following the 2021 Marshall Fire in Colorado, this study was conducted to better understand private well and plumbing damage and to develop public health guidance. More than 20 post‐fire drinking water well guidance documents with varied recommendations were found. Approximately 227 wells were located in the fire footprint. Seventeen properties were visited, and a subset of wells were sampled for organic and inorganic contaminants. Property debris was also collected. Benzene, toluene, and 19 semi‐volatile organic compounds (SVOCs) were detected in water extracts of property debris. No wells contained volatile organic compound contamination. Two shallow wells (12 and 15 ft) had debris contamination; one well contained notable SVOC contamination. One multi‐home unregulated well system was extensively damaged, lost pressure, and had not been repressurized 11 months after the fire due to financial and technical challenges. Study results highlight the need for follow‐up work to understand well system damage and household response. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email