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51.
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Ewa Sokol Ayanna U. Jackson R. Graham Cooks 《Central European Journal of Chemistry》2011,9(5):790-797
Desorption electrospray ionization (DESI), an established ambient ionization method in mass spectrometry (MS) for the analysis
of organic compounds, is applied here to trace detection of inorganic salts, including inorganic oxidants. In-situ surface
analysis of targeted compounds, including nitrogen-, halogen- and sulfur-salts, down to sub-nanogram levels, was performed
using DESI-MS. Successful experiments were carried out in both the negative and the positive ion modes; simple anions and
cations as well as small cluster ions were observed. Various surfaces are examined and surface porosity effects were briefly
explored. Absolute detection limits on porous polytetrafluoroethylene (PTFE) of 120 pg (surface concentration 0.07 ng mm−2) and 50 pg (surface concentration 0.03 ng mm−2), were achieved for sodium chlorate and sodium perchlorate, respectively. The compounds of interest were examined in the
presence of a hydrocarbon mixture to assess matrix effects: only a two- or three-fold decrease in the target ion intensity
was observed. Commercial fireworks were analyzed to determine perchlorate salts in complex mixtures. This work demonstrates
the potential applicability of ambient ionization mass spectrometry to forensic investigations involving improvised explosives.
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Molecular SIMS, an important development in mass spectrometry of complex organic molecules, has application to the analysis of reactive adiayers on surfaces. We report here the discovery by SIMS of thiophene self-hydrogenation on silver foil. 相似文献
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The double quadrupole mass spectrometer is shown to be applicable to differentiation of isomeric C5 ketones and for the detection of camphor in a drug and a cosmetic. Detection limits in the picogram range are demonstrated. The similarity between the low-energy QQ collision-induced dissociations and those of high-energy MIKE spectrometry facilitates use of both techniques for mass spectrometry/mass spectrometry. 相似文献
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A dipolar ac signal applied to the split outer electrode of an Orbitrap mass spectrometer at the axial resonance frequency causes excitation of ion axial motion and either eventual ion ejection from the trap, if applied in phase with ion motion, or de-excitation, if applied 180 degrees out of phase. Both de-excitation and excitation may be achieved mass-selectively. The extent of ion axial de-excitation depends on the ac amplitude and on the number of cycles applied; sufficient de-excitation can be accomplished such that the ion signal cannot be observed above baseline noise. After de-excitation, the ions remain trapped and in rapid orbital (but not axial) motion, which allows them to be re-excited coherently by application of a second ac waveform allowing the signal again to be observed. Both broad-band and narrow-band waveforms have been used to de-excite and to re-excite ion motion. Using narrow-band waveforms, selective de-excitation and re-excitation can be performed with unit mass selection, leaving an adjacent 13C isotopic peak unaffected. The origin and potential applications of these new capabilities is delineated. 相似文献
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Extractive electrospray ionization for direct analysis of undiluted urine, milk and other complex mixtures without sample preparation 总被引:7,自引:0,他引:7
On-line droplet-droplet extraction occurs when a sample spray intersects a reagent electrospray; this allows continuous analysis of trace amounts of compounds directly in complex matrices including undiluted urine, milk and polluted water over extended periods of time. 相似文献