F Grases1, O Söhnel2, M Zelenková3, A Rodriguez4. 1. Laboratory of Renal Lithiasis Research, University Institute of Health Sciences (UNICS-IdisPa), University of Balearic Islands, Palma Mallorca, Spain. fgrases@uib.es. 2. Faculty of Environmental Studies, University of J. E. Purkyně, Ústí n.L., Czech Republic. 3. TOSEDA s.r.o., Pardubice, Czech Republic. 4. Laboratory of Renal Lithiasis Research, University Institute of Health Sciences (UNICS-IdisPa), University of Balearic Islands, Palma Mallorca, Spain.