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Trufelli H Famiglini G Termopoli V Cappiello A 《Analytical and bioanalytical chemistry》2011,400(9):2933-2941
This paper focuses on the development of a novel approach to analyze underivatized fatty acids in human plasma. The method
is based on liquid–liquid extraction followed by reversed phase liquid chromatography coupled to direct-electron ionization
mass spectrometry (LC-Direct-EI-MS). The assay is validated. Calibrations show satisfactory linearity and precision in the
investigated range of linearity. Recoveries span from 75% to 104%. The method limits of detection, varying from 0.53 to 5.35 μM,
are satisfactory for the quantitation of non-esterified fatty acids (NEFAs) in plasma at physiological levels. The method
has been successfully applied to the NEFAs profiling of plasma samples from healthy adult volunteers and subjects affected
by diabetes mellitus. Compared with published protocols based on gas chromatography–mass spectrometry and liquid chromatography
coupled to electrospray ionization mass spectrometry, this method does not require derivatization and does not show matrix
effects, thus simplifying sample preparation procedure and reducing the total time of analysis to approximately 90 min. In
addition, Direct-EI-MS allows the acquisition of high-quality NIST library-matchable EI spectra, allowing an easy-to-obtain
identification of the target NEFAs. 相似文献
174.
Claudia Schepler Martin Sklorz Johannes Passig Giorgio Famiglini Achille Cappiello Ralf Zimmermann 《Analytical and bioanalytical chemistry》2013,405(22):6953-6957
Electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo-ionization (APPI) are the most important techniques for the ionization of liquid samples. However, working under atmospheric pressure conditions, all these techniques involve some chemical rather than purely physical processes, and therefore, side reactions often yield to matrix-dependent ionization efficiencies. Here, a system is presented that combines both soft single-photon ionization (SPI) and hard 70 eV electron impact ionization (EI) of dissolved compounds under vacuum conditions. A quadrupole mass spectrometer was modified to enable direct EI, a technique developed by Cappiello et al. to obtain library-searchable EI mass spectra as well as soft SPI mass spectra of sample solutions. An electron beam-pumped rare gas excimer lamp working at 126 nm was used as well as a focusable vacuum UV light source for single-photon ionization. Both techniques, EI and SPI, were applied successfully for flow injection experiments providing library-matchable EI fragment mass spectra and soft SPI mass spectra, showing dominant signals for the molecular ion. Four model compounds were analyzed: hexadecane, propofol, chlorpropham, and eugenol, with detection limits in the picomolar range. This novel combination of EI and SPI promises great analytical benefits, thanks to the possibility of combining database alignment for EI data and molecular mass information provided by SPI. Possible applications for the presented ionization technology system are a matrix-effect-free detection and a rapid screening of different complex mixtures without time-consuming sample preparation or separation techniques (e.g., for analysis of reaction solutions in combinatorial chemistry) or a switchable hard (EI) and soft (SPI) MS method as detection step for liquid chromatography. Figure
Scheme of the interface for introduction of liquid samples for vacuum photoionization/electron impact ionization MS 相似文献
175.
Miriam Di Martino Lucia Sessa Martina Di Matteo Barbara Panunzi Stefano Piotto Simona Concilio 《Molecules (Basel, Switzerland)》2022,27(17)
Azo molecules, characterized by the presence of a -N=N- double bond, are widely used in various fields due to their sensitivity to external stimuli, ch as light. The emergence of bacterial resistance has pushed research towards designing new antimicrobial molecules that are more efficient than those currently in use. Many authors have attempted to exploit the antimicrobial activity of azobenzene and to utilize their photoisomerization for selective control of the bioactivities of antimicrobial molecules, which is necessary for antibacterial therapy. This review will provide a systematic and consequential approach to coupling azobenzene moiety with active antimicrobial molecules and drugs, including small and large organic molecules, such as peptides. A selection of significant cutting-edge articles collected in recent years has been discussed, based on the structural pattern and antimicrobial performance, focusing especially on the photoactivity of azobenzene and the design of smart materials as the most targeted and desirable application. 相似文献
176.