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@ARTICLE{Thiele:62860,
      author       = {Thiele, B. and Füllner, K. and Stein, N. and Oldiges, M.
                      and Kuhn, A. J. and Hofmann, D.},
      title        = {{A}nalysis of amino acids without derivatization in barley
                      extracts by {LC}-{MS}-{MS}},
      journal      = {Analytical and bioanalytical chemistry},
      volume       = {391},
      issn         = {1618-2642},
      address      = {Berlin},
      publisher    = {Springer},
      reportid     = {PreJuSER-62860},
      pages        = {2663 - 2672},
      year         = {2008},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {A method has been developed for quantification of 20 amino
                      acids as well as 13 (15)N-labeled amino acids in barley
                      plants. The amino acids were extracted from plant tissues
                      using aqueous HCl-ethanol and directly analyzed without
                      further purification. Analysis of the underivatized amino
                      acids was performed by liquid chromatography
                      (LC)-electrospray ionization (ESI) tandem mass spectrometry
                      (MS-MS) in the positive ESI mode. Separation was achieved on
                      a strong cation exchange column (Luna 5micro SCX 100A) with
                      30 mM ammonium acetate in water (solvent A) and $5\%$ acetic
                      acid in water (solvent B). Quantification was accomplished
                      using d (2)-Phe as an internal standard. Calibration curves
                      were linear over the range 0.5-50 microM, and limits of
                      detection were estimated to be 0.1-3.0 microM. The
                      mass-spectrometric technique was employed to study the
                      regulation of amino acid levels in barley plants grown at 15
                      degrees C uniform root temperature (RT) and 20-10 degrees C
                      vertical RT gradient (RTG). The LC-MS-MS results
                      demonstrated enhanced concentration of free amino acids in
                      shoots at 20-10 degrees C RTG, while total free amino acid
                      concentration in roots was similarly low for both RT
                      treatments. (15)NO(3) (-) labeling experiments showed lower
                      (15)N/(14)N ratios for Glu, Ser, Ala and Val in plants grown
                      at 20-10 degrees C RTG compared with those grown at 15
                      degrees C RT.},
      keywords     = {Amino Acids: analysis / Calibration / Cations: chemistry /
                      Chromatography, Ion Exchange: methods / Hordeum: chemistry /
                      Hordeum: metabolism / Nitrogen Isotopes / Plant Extracts:
                      analysis / Plant Leaves: chemistry / Plant Leaves:
                      metabolism / Plant Roots: chemistry / Plant Roots:
                      metabolism / Plant Shoots: chemistry / Plant Shoots:
                      metabolism / Reproducibility of Results / Spectrometry,
                      Mass, Electrospray Ionization: methods / Tandem Mass
                      Spectrometry: methods / Amino Acids (NLM Chemicals) /
                      Cations (NLM Chemicals) / Nitrogen Isotopes (NLM Chemicals)
                      / Plant Extracts (NLM Chemicals) / J (WoSType)},
      cin          = {ZCH / ICG-3 / IBT-2},
      ddc          = {540},
      cid          = {I:(DE-Juel1)ZCH-20090406 / I:(DE-Juel1)ICG-3-20090406 /
                      I:(DE-Juel1)VDB56},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Biochemical Research Methods / Chemistry, Analytical},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:18506428},
      UT           = {WOS:000258083900030},
      doi          = {10.1007/s00216-008-2167-9},
      url          = {https://juser.fz-juelich.de/record/62860},
}