Analysis In Real Time Ion Source Research Articles

Structural features of liquefaction residue from Shenmu-Fugu subbituminous coal

Liquefaction residue (LRSFSBC) from Shenmu-Fugu subbituminous coal was ultrasonically extracted with petroleum ether, methanol, cyclohexane, ethyl acetate, acetone, carbon disulfide (CDS) and isometric CDS/acetone mixture (IMCDSAM), respectively. A number of alkanes, arenes, arenols, alkanols, alkenones, esters, and nitrogen-containing organic compounds were identified according to the analyses with Fourier transform infrared spectrometer, gas chromatograph/mass spectrometer, direct analysis in real-time ionization source coupled with ion trap mass spectrometer, and solid-state 13C nuclear magnetic resonance (SS 13C NMR). The tetra- and penta-substituted anthracene or phenanthrene unit could be the average structures in LRSFSBC by SS 13C NMR analysis. The main intermolecular interactions among the organic species in LRSFSBC are π–hydrogen bonds and π–π interactions. These interactions are also the cause for “capsule” formation. Stronger interactions between LRSFSBC and solvents, especially CDS and IMCDSAM, destroyed the interactions and thereby led to high extract yields.

Identification of Nitro Explosives by Direct Analysis in Real-Time Time-of-Flight Mass Spectrometry

ABSTRACTNitro compounds such as 2,4,6-trinitrotoluene, cyclotrimethylene trinitramine, and pentaerythritol tetranitrate are common ingredients of high explosives found in homeland security threats, minefields, and industrial materials. This study aims at developing a convenient surface analysis method for rapid identification of these compounds by direct analysis in real time coupled with time-of-flight mass spectrometry. The possible ionization mechanisms and fragmentation pathways using the direct analysis in real-time ionization source were developed for each compound based on the ions produced by in-source collision-induced dissociation and acquired by a time-of-flight mass spectrometer. These compounds release nitro groups and form nitroless characteristic fragments with other nitro adducts during in-source collision-induced dissociation processes. The characteristic ion [M + C2H4N3O2]− produced by cyclotrimethylene trinitramine was observed for the first time to our best knowledge. Direct analysis in real-time time-of-flight mass spectrometry has provided rapid identification of residues from various samples from explosion scenes and, therefore, is a potential powerful screening tool for criminal evidence.

Mass Spectrometry of Spacecraft Contamination Using Direct Analysis in Real-Time Ion Source

Spacecraft contamination was analyzed using mass spectrometry with the direct analysis in real-time ionization source. This source uses metastable helium for soft ionization and to mediate atmospheric desorption of samples into a mass spectrometer. The sampling methodology allows polymers to be assessed for the presence of vacuum labile components. Vacuum labile residues are significant sources of contamination on spacecraft optics, science instruments, and thermal control surfaces. The methodology also provides sensitive analysis of molecular contamination on spacecraft surfaces using existing spacecraft sampling procedures. This provides identification information for a wide range of molecular components including biomarker compounds.

Characterizations of the Extracts from Geting Bituminous Coal by Spectrometries

Geting bituminous coal (GBC) was sequentially extracted with petroleum ether, carbon disulfide (CDS), methanol, acetone, and isometric CDS/acetone mixed solvent at room temperature to afford extracts 1–5 (E1–E5) and residue. Detailed characterizations of the extracts were performed with a gas chromatography/mass spectrometer (GC/MS), Fourier transform infrared (FTIR) spectrometer, and direct analysis in real-time ionization source (DARTIS) coupled to an ion-trap mass spectrometer (ITMS). GBC and its residue were also analyzed with the FTIR spectrometer. Particle sizes of the residue were significantly reduced compared to those of GBC according to the observation with a scanning electron microscope. Arenes with 1–4 rings and more condensed arenes were enriched into E1 and E2, respectively, while more heteroatom-containing organic species were detected in other extracts, especially in E3 and E4 according to GC/MS analysis. The extracts, especially E1–E4, contain more aliphatic moieties and less aromatic moi...