The cyclization of di-(2,6-difluorophenyl)maleindinitrile with magnesium(II) and zinc(II) acetates in boiling ethylene glycol is applied to synthesize Mg(II) and Zn(II) complexes of the ...octa-(2,6-difluorophenyl)tetraazaporphyrin. The compounds are identified by UV-Vis, sup.1H NMR, and mass spectrometry methods. A comparative analysis is performed of the spectral-luminescent properties of magnesium and zinc octaaryltetraazaporphyrinates and their dependence on the number and position of the fluorine atoms in the macrocycle phenyl fragments. The DFT method is used to optimize the geometry of the synthesized complexes. Machine learning methods and QSPR are applied to predict the Soret band wavelength in the UV-V is spectra of the complexes described.
Reaction of YbCpsub.2(dme) (Cp = cyclopentadienyl, dme = 1,2 dimethoxyethane) with bis(diphenylphosphano)methane dioxide (Hsub.2dppmOsub.2) leads to deprotonation of the ligand Hsub.2dppmOsub.2 and ...oxidation of ytterbium, forming an extremely air-sensitive product, Ybsup.III(HdppmOsub.2)sub.3 (1), a six-coordinate complex with three chelating (OPCHPO) HdppmOsub.2 ligands. Complex 1 was also obtained by a redox transmetallation/protolysis synthesis from metallic ytterbium, Hg(Csub.6Fsub.5)sub.2, and Hsub.2dppmOsub.2. In a further preparation, the reaction of Yb(Csub.6Fsub.5)sub.2 with Hsub.2dppmOsub.2, not only yielded compound 1, but also gave a remarkable tetranuclear cage, Ybsub.4(µ-HdppmOsub.2)sub.6(µ-F)sub.6 (2) containing two Yb(µ-F)sub.2 rhombic units linked by two fluoride ligands and the tetranuclear unit is encapsulated by six bridging HdppmOsub.2 donors. The fluoride ligands of the cage result from C-F activation of pentafluorobenzene and concomitant formation of p-Hsub.2Csub.6Fsub.4 and m-Hsub.2Csub.6Fsub.4, the last being an unexpected product.
Understanding the cycling of C and N in soils is important for maintaining soil fertility while also decreasing greenhouse gas emissions, but much remains unknown about how organic matter (OM) is ...stabilized in soils. We used nano‐scale secondary ion mass spectrometry (NanoSIMS) to investigate the changes in C and N in a Vertisol and an Alfisol incubated for 365 days with 13C and 15N pulse labeled lucerne (Medicago sativa L.) to discriminate new inputs of OM from the existing soil OM. We found that almost all OM within the free stable microaggregates of the soil was associated with mineral particles, emphasizing the importance of organo‐mineral interactions for the stabilization of C. Of particular importance, it was also found that 15N‐rich microbial products originating from decomposition often sorbed directly to mineral surfaces not previously associated with OM. Thus, we have shown that N‐rich microbial products preferentially attach to distinct areas of mineral surfaces compared to C‐dominated moieties, demonstrating the ability of soils to store additional OM in newly formed organo‐mineral associations on previously OM‐free mineral surfaces. Furthermore, differences in 15N enrichment were observed between the Vertisol and Alfisol presumably due to differences in mineralogy (smectite‐dominated compared to kaolinite‐dominated), demonstrating the importance of mineralogy in regulating the sorption of microbial products. Overall, our findings have important implications for the fundamental understanding of OM cycling in soils, including the immobilization and storage of N‐rich compounds derived from microbial decomposition and subsequent N mineralization to sustain plant growth.
Understanding how organic carbon (C) and nitrogen (N) are cycled in soils is important for decreasing emissions of greenhouse gases and for maintaining soil fertility. We used nano‐scale secondary ion mass spectrometry (NanoSIMS) to examine changes in C and N in two soils. We have found that N‐rich compounds derived from microbial degradation often sorb directly to mineral surfaces not previously associated with organic matter (OM). This is important as it shows the ability of soils to store additional OM in new associations, with this information also assisting in the development of models for OM and nutrient cycling.
Advances in drugs of abuse testing Tamama, Kenichi
Clinica chimica acta,
March 2021, 2021-Mar, 2021-03-00, 20210301, Letnik:
514
Journal Article
Recenzirano
•Saliva, sweat, hair, and meconium are emerging types of specimen for drug testing.•LC-MSMS becomes a new gold standard for confirmatory drug testing.•LC-hybrid-Tof-MS is usable for comprehensive ...drug screening.•Miniature ambient ionization MS can quickly analyze biological specimens.•Miniature ambient ionization MS is promising for rapid drugs of abuse testing.
Drugs of abuse testing is widely used clinically and forensically. Urine is the preferred type of specimen for drugs of abuse screening, but saliva, sweat, hair, and meconium are emerging types of specimens. GC–MS has been used as a gold standard for confirmatory drug testing, but LC-tandem-MS can analyze more diverse types of analytes than GC–MS. Thus, LC-tandem-MS becomes a new gold standard for confirmatory drug testing. Unlike GC–MS, LC-tandem-MS is not suited for non-targeted comprehensive drug screening. But with the advent of high-resolution-MS such as Tof-MS, which can discriminate the compounds of similar molecular masses but with different formulas, LC-hybrid-Tof-MS is usable for non-targeted comprehensive drug screening. Another technical advancement is the advent of miniature ambient ionization MS, which can analyze biological specimens including urine within one minute. Thus these mass spectrometers are promising for rapid drugs of abuse testing in a POC setting.
Native mass spectrometry (MS) is becoming an important integral part of structural proteomics and system biology research. The approach holds great promise for elucidating higher levels of protein ...structure: from primary to quaternary. This requires the most efficient use of tandem MS, which is the cornerstone of MS-based approaches. In this work, we advance a two-step fragmentation approach, or (pseudo)-MS(3), from native protein complexes to a set of constituent fragment ions. Using an efficient desolvation approach and quadrupole selection in the extended mass-to-charge (m/z) range, we have accomplished sequential dissociation of large protein complexes, such as phosporylase B (194 kDa), pyruvate kinase (232 kDa), and GroEL (801 kDa), to highly charged monomers which were then dissociated to a set of multiply charged fragmentation products. Fragment ion signals were acquired with a high resolution, high mass accuracy Orbitrap instrument that enabled highly confident identifications of the precursor monomer subunits. The developed approach is expected to enable characterization of stoichiometry and composition of endogenous native protein complexes at an unprecedented level of detail.
Peptide sequencing is the basis of mass spectrometry-driven proteomics. Here we show that in the linear ion trap-orbitrap mass spectrometer (LTQ Orbitrap) peptide ions can be efficiently fragmented ...by high-accuracy and full-mass-range tandem mass spectrometry (MS/MS) via higher-energy C-trap dissociation (HCD). Immonium ions generated via HCD pinpoint modifications such as phosphotyrosine with very high confidence. Additionally we show that an added octopole collision cell facilitates de novo sequencing.
Mass spectrometry imaging (MSI) is a powerful, label-free technique that provides detailed maps of hundreds of molecules in complex samples with high sensitivity and subcellular spatial resolution. ...Accurate quantification in MSI relies on a detailed understanding of matrix effects associated with the ionization process along with evaluation of the extraction efficiency and mass-dependent ion losses occurring in the analysis step. We present a critical summary of approaches developed for quantitative MSI of metabolites, lipids, and proteins in biological tissues and discuss their current and future applications.
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