Atmospheric pressure chemical ionization and atmospheric pressure photoionization for simultaneous mass spectrometric analysis of microbial respiratory ubiquinones and menaquinones

Authors

  • Roland Geyer,

    Corresponding author
    1. Center for Biomarker Analysis, University of Tennessee, 10515 Research Drive, Knoxville, Tennessee 37932-2575, USA
    2. Groundwater Microbiology Group, UFZ Centre for Environmental Research, Leipzig-Halle, D-06120 Halle, Germany
    • Groundwater Microbiology Group, UFZ Centre for Environmental Research Leipzig-Halle, D-06120 Halle, Germany.
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  • Aaron D. Peacock,

    1. Center for Biomarker Analysis, University of Tennessee, 10515 Research Drive, Knoxville, Tennessee 37932-2575, USA
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  • David C. White,

    1. Center for Biomarker Analysis, University of Tennessee, 10515 Research Drive, Knoxville, Tennessee 37932-2575, USA
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  • Cory Lytle,

    1. Thermo Electron Corporation, 1400 Northpoint Parkway, Suite 10, West Palm Beach, Florida 33407, USA
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  • Gary J. Van Berkel

    1. Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6131, USA
    2. Graduate School of Genome Science and Technology, University of Tennessee and Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830-8026, USA
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Abstract

An atmospheric pressure photoionization (APPI) source and an atmospheric pressure chemical ionization (APCI) source were compared for the selective detection of microbial respiratory ubiquinone and menaquinone isoprenologues using tandem mass spectrometry. Ionization source- and compound mass-dependent parameters were optimized individually for both sources, using the available quinone standards. Detection levels for the two ion sources were determined with ubiquinone-6 (UQ6) and menaquinone-4 (MK4, vitamin K2) standards using flow injection analysis and selected reaction monitoring (SRM). With APPI the calculated lower limit of detection (LLOD) was 1.7 fmol µl−1 for UQ6 and 2.2 fmol µl−1 for MK4 at a signal-to-noise ratio of 3. These LLODs were at least three times lower than with APCI. The selectivity of detection afforded by SRM detection reduced complex mixture analysis to 3 min per sample by eliminating the need for chromatographic separations. The detection method was successfully applied to quinone quantification in a variety of environmental samples and cell cultures. Adequate amounts of respiratory quinones can be extracted and quantified from samples containing as low as 2 × 107 cells. Copyright © 2004 John Wiley & Sons, Ltd.

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