High solid probe mass spectrometry

Laser ionization mass spectrometry or laser microprobing (LIMS) is a microanalyt-ical technique used to rapidly characterize the elemental and, sometimes, molecular composition of materials. It is based on the ability of short high-power laser pulses (-10 ns) to produce ions from solids. The ions formed in these brief pulses are analyzed using a time-of-flight mass spectrometer. The quasi-simultaneous collection of all ion masses allows the survey analysis of unknown materials. The main applications of LIMS are in failure analysis, where chemical differences between a contaminated sample and a control need to be rapidly assessed. The ability to focus the laser beam to a diameter of approximately 1 mm permits the application of this technique to the characterization of small features, for example, in integrated circuits. The LIMS detection limits for many elements are close to 10 at/cm, which makes this technique considerably more sensitive than other survey microan-alytical techniques, such as Auger Electron Spectroscopy (AES) or Electron Probe Microanalysis (EPMA). Additionally, LIMS can be used to analyze insulating sam-... 

Bray KL (2001) High Pressure Probes of Electronic Structure and Luminescence Properties of Transition Metal and Lanthanide Systems. 213 1-94 Bronstein LM (2003) Nanoparticles Made in Mesoporous Solids. 226 55-89 Bronstrup M (2003) High Throughput Mass Spectrometry for Compound Characterization in Drug Discovery. 225 275-294... 

State-of-the-art ToF-MS employs reflection lenses and delayed extraction [176] to improve resolution by minimising small differences in ion energies, and in these cases up to 12000 mass resolution (FWHM, m/z 600) is available. This is sufficient for most modern applications. Solid probe ToF-MS (or direct inlet high-resolution mass spectrometry, DI-HRMS) is a breakthrough. DIP-ToFMS is a thermal separation technique. Advantages of DIP-ToFMS are ... 

Mass spectrometry combines exquisite sensitivity with a precision that often depends more on the uncertainties of sampling and sample preparation than on those of the method itself. Mass spectrometry is a supreme identification and recognition method in polymer/additive analysis through highly accurate masses and fragmentation patterns quantitation is its weakness. Direct mass spectrometry of complex polymeric matrices is feasible, yet not often pursued. Solid probe ToF-MS (DI-HRMS) is a breakthrough. Where used routinely, mass spectrometrists are usually still in charge. At the same time, however, costs need to be watched. 

Transport phenomena occur particularly when transporting the vapors themselves. They disappear completely when the sample is inserted directly into the signal generation source, where it is evaporated thermally. This approach is known from work with graphite or metal probes in atomic absorption, where for example W wire cups and loops are used. The technique is also used in plasma spectrometry with the inductively coupled plasma (ICP), both in atomic emission [189-191] and in mass spectrometry [192]. Its absolute power of detection is extremely high and the technique can be used both for the analysis of dry solution residues as well as for the volatilization of microamounts of solids. 

Mass spectra were determined for the crude extract and for compounds A1 and B1 from the HPLC analysis. The solid-inlet probe mass N spectra did not exactly correspond to the mass spectra of peaks A and B from the GLC analysis. Peaks A1 and B gave molecular ions of 346 and 374 m/z, respectively, exactly 44 units higher than peaks A and B. High resolution mass spectrometry showed the difference to be CO. Thus, these data implied that compounds A1 and B1 were undergoing decarboxylation upon gas chromatography and that the resulting peaks A and B were decomposition products of Av and Bv. 

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