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1.
Anal Chem ; 81(11): 4456-67, 2009 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-19408912

RESUMO

An in-house-built ion trap mass spectrometer combined with a soft ionization source has been set up and tested. As ionization source, an electron beam pumped vacuum UV (VUV) excimer lamp (EBEL) was used for single-photon ionization. It was shown that soft ionization allows the reduction of fragmentation of the target analytes and the suppression of most matrix components. Therefore, the combination of photon ionization with the tandem mass spectrometry (MS/MS) capability of an ion trap yields a powerful tool for molecular ion peak detection and identification of organic trace compounds in complex matrixes. This setup was successfully tested for two different applications. The first one is the detection of security-relevant substances like explosives, narcotics, and chemical warfare agents. One test substance from each of these groups was chosen and detected successfully with single photon ionization ion trap mass spectrometry (SPI-ITMS) MS/MS measurements. Additionally, first tests were performed, demonstrating that this method is not influenced by matrix compounds. The second field of application is the detection of process gases. Here, exhaust gas from coffee roasting was analyzed in real time, and some of its compounds were identified using MS/MS studies.

2.
Anal Bioanal Chem ; 395(6): 1795-807, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19588128

RESUMO

For the detection of security-relevant substances at low concentrations in complex matrices, coupling of thermal desorption-single photon ionization-ion trap mass spectrometry (TD-SPI-ITMS) was successfully tested. The main advantage of taking solid samples with a wipe pad followed by thermal desorption is the low detection limit by enhanced vapor pressure. Single photon ionization is a soft ionization technique which reduces the target ion fragmentation and shields bulk components with high ionization energies (IE) like nitrogen yielding to clearly arranged mass spectra with significant high mass peaks. To obtain low false-positive and false-negative rates, especially necessary for security-relevant substances, the ion trap mass spectrometer allows identification of signals with MS/MS studies. In this concept, the soft ionization technique fits well with the MS/MS studies, as peaks with high masses are generated yielding significant MS/MS fragments. For the ionization, photon energies between about 8 eV (155 nm) and 12 eV (103 nm) were generated with electron-beam-pumped rare gas excimer lamps (EBEL). Depending on the rare gas used, light with different photon energy is generated, adapted to the substances of interest. So, even most narcotics, having relatively low IEs, can be ionized with 8.4 eV photons without massive fragmentation. For most explosives, photons with higher energy must be used as their IEs are higher. In this work, a mobile setup with a commercial ion trap mass spectrometer has been developed and tested. Even a first real-scenario measurement campaign was accomplished successfully proving the field-suitability of the system.

3.
Appl Spectrosc ; 67(8): 860-72, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23876725

RESUMO

The photoionization properties of the pharmaceutically relevant substances amantadine, diazepam, dimethyltryptamine, etomidate, ketamine, mescaline, methadone, and propofol were determined. At beamline U125/2-10m-NIM of the BESSY II synchrotron facility (Berlin, Germany) vacuum ultraviolet (VUV) photoionization spectra were recorded in the energy range 7.1 to 11.9 eV (174.6 to 104.2 nm), showing the hitherto unknown ionization energies and fragmentation appearance energies of the compounds under investigation. Furthermore, (1+1)-resonance-enhanced multiphoton ionization (REMPI) spectra of selected compounds (amantadine, diazepam, etomidate, ketamine, and propofol) were recorded by a continuous scan in the energy range between 3.6 and 5.7 eV (345 to 218 nm) using a tunable optical parametric oscillator (spectral resolution: 0.1 nm) laser system. The resulting REMPI wavelength spectra of these compounds are discussed and put into context with already known UV absorption data. Time-of-flight mass spectrometry was used for ion detection in both experiments. Finally, the implications of the obtained physical-chemical results for potential analytical applications are discussed. In this context, fast detection approaches for the considered compounds from breath gas using photoionization mass spectrometry and a rapid pre-concentration step (e.g., needle trap device) are of interest.


Assuntos
Preparações Farmacêuticas/análise , Processos Fotoquímicos , Fótons , Espectrometria de Massas por Ionização por Electrospray/métodos , Análise Espectral/métodos , Síncrotrons , Humanos
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