[1] Ernst Moritz Arndt Univ Greifswald, Inst Biochem, Felix Hausdorff Str 4, D-17489 Greifswald, Germany
[2] Georg August Univ Gottingen, Inst Organ & Biomol Chem, Zent Anal Massenspektrometrie, Tammannstr 2, D-37077 Gottingen, Germany
[3] Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Postfach 3329, D-38023 Braunschweig, Germany