1. Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, Murcia, Spain;
2. Department of Chemical Sciences, Medical University of Plovdiv, Plovdiv, Bulgaria;
3. Institute of Laboratory Research on Geomaterials, Comenius University in Bratislava, Bratislava, Slovak Republic;
4. Department of Analytical Chemistry, Pavol Jozef Šafárik University in Košice, Košice, Slovak Republic