1. Department of Chemistry, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
2. Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund, Otto-Hahn-Strasse 6, 44221 Dortmund, Germany
3. Department of Chemistry, Busitema University, P.O. Box 236, Tororo, Uganda
4. School of Biological Sciences, University of Nairobi, Nairobi, Kenya