[1] Czech Acad Sci, Inst Geol, Rozvojova 269, Prague 16500 6, Czech Republic
[2] Czech Acad Sci, Nucl Phys Inst, Hlavni 130, Husinec Rez 25068, Czech Republic
[3] Karl Franzens Univ Graz, Inst Chem, Univ Pl 1, A-8010 Graz, Austria
[4] Czech Acad Sci, Inst Microbiol, Videnska 1083, Prague 14220 4, Czech Republic
[5] Univ Chem & Technol Prague, Dept Biochem & Microbiol, Tech 3, Prague 16628, Czech Republic
[6] Univ Chem & Technol, Dept Analyt Chem, Tech 5, Prague 16628, Czech Republic
[7] Univ Ghent, Dept Chem, Atom & Mass Spectrometry Res Unit, Krijgslaan 281-S12, B-9000 Ghent, Belgium