Home  About us  Contact
 

Photoionization Mass Spectrometry (photoionization + mass_spectrometry)

Distribution by Scientific Domains
Chemistry100%

Kinds of Photoionization Mass Spectrometry

  • atmospheric pressure photoionization mass spectrometry
    		•
  • pressure photoionization mass spectrometry
    		•

    Selected Abstracts

    Photoionization studies on various quinones by an infrared laser desorption/tunable VUV photoionization TOF mass spectrometry

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 12 2008
    Yang Pan
    Abstract Photoionization and dissociative photoionization characters of six quinones, including 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthroquinone (PQ), 9,10-anthraquinone (AQ), benz[a]- anthracene-7,12-dione (BAD) and 1,2-acenaphthylenedione (AND) have been studied with an infrared laser desorption/tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (IR LD/VUV PIMS) technique. Mass spectra of these compounds are obtained at different VUV photon energies. Consecutive losses of two carbon monoxide (CO) groups are found to be the main fragmentation pathways for all the quinones. Detailed dissociation processes are discussed with the help of ab initio B3LYP calculations. Ionization energies (IEs) of these quinones and appearance energies (AEs) of major fragments are obtained by measuring the photoionization efficiency (PIE) spectra. The experimental results are in good agreement with the theoretical data. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Effect of eluent on the ionization efficiency of flavonoids by ion spray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization mass spectrometry

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 12 2001
    Jussi-Pekka Rauha
    Abstract The effect of nine different eluent compositions on the ionization efficiency of five flavonoids was studied using ion spray (IS), atmospheric pressure chemical ionization (APCI), and the novel atmospheric pressure photoionization (APPI), in positive and negative ion modes. The eluent composition had a great effect on the ionization efficiency, and the optimal ionization conditions were achieved in positive ion IS and APCI using 0.4% formic acid (pH 2.3) as a buffer, and in negative ion IS and APCI using ammonium acetate buffer adjusted to pH 4.0. For APPI work, the eluent of choice appeared to be a mixture of organic solvent and 5 mM aqueous ammonium acetate. The limits of detection (LODs) were determined in scan mode for the analytes by liquid chromatography/mass spectrometry using IS, APCI and APPI interfaces. The results show that negative ion IS with an eluent system consisting of acidic ammonium acetate buffer provides the best conditions for detection of flavonoids in mass spectrometry mode, their LODs being between 0.8 and 13 µM for an injection volume of 20 µl. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Feasibility of capillary liquid chromatography/microchip atmospheric pressure photoionization mass spectrometry in analyzing anabolic steroids in urine samples

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2010
    Linda L. Ahonen
    We examined the feasibility of capillary liquid chromatography/microchip atmospheric pressure photoionization tandem mass spectrometry (capLC/µAPPI-MS/MS) for the analysis of anabolic steroids in human urine. The urine samples were pretreated by enzymatic hydrolysis (with , -glucuronidase from Helix pomatia), and the compounds were liquid-liquid extracted with diethyl ether. After separation the compounds were vaporized by microchip APPI, photoionized by a 10,eV krypton discharge lamp, and detected by selected reaction monitoring. The capLC/µAPPI-MS/MS method showed good sensitivity with detection limits at the level of 1.0,ng,mL,1, good linearity with correlation coefficients between 0.9954 and 0.9990, and good repeatability with relative standard deviations below 10%. These results demonstrate that microchip APPI combined with capLC/MS/MS provides a new potential method for analyzing non-polar and neutral compounds in biological samples. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    The characterization of selected drugs with infrared laser desorption/tunable synchrotron vacuum ultraviolet photoionization mass spectrometry

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2008
    Yang Pan
    Some selected drugs including captopril, fudosteine and racecadotril have been analyzed by infrared (IR) laser desorption/tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS). The molecular ions of captopril and racecadotril are exclusively observed without any fragments at near threshold single-photon ionization (SPI). However, fudosteine easily forms fragments even at a photon energy near the ionization threshold, indicating the instability of its molecular ion. For these drugs, a number of fragments are yielded with the increase of photon energy. The structures of such fragments proposed by IR LD/VUV PIMS are supported by electron ionization time-of-flight mass spectrometry (EI-TOFMS) results. Fragmentation pathways are discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Determination of perfluorooctane sulfonate in river water by liquid chromatography/atmospheric pressure photoionization mass spectrometry by automated on-line extraction using turbulent flow chromatography

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2003
    Masahiko Takino
    A simple, fast and sensitive liquid chromatography/atmospheric pressure photoionization mass spectrometry (LC/APPI-MS) method, with automated on-line extraction using turbulent flow chromatography (TFC), was developed for the determination of perfluorooctane sulfonate (PFOS) in river water. In this method, following an on-line extraction by injection onto a column under TFC conditions, PFOS is back-flushed onto a reversed-phase column via on-line column switching, and resolved chromatographically at a laminar flow rate of 1,mL min,1. Using this tandem LC-LC/APPI-MS system the extraction, separation and selective detection of PFOS in river water could be achieved with satisfactory selectivity and sensitivity. The limit of detection (LOD) (S/N,=,3) and the limit of quantitation (LOQ) (S/N,=,10)were 5.35 and 17.86,pg,mL,1. The described procedure was very simple since no off-line sample preparation was required, total analysis time being 18.75,min. Copyright © 2003 John Wiley & Sons, Ltd. [source]