1. Department of Chemistry, Mekdela Amba University, P.O. BOX 32, Mekane Selam, Ethiopia
2. Department of Chemistry, Bahir Dar University, P.O. BOX 79, Bahir Dar, Ethiopia
3. Department of Chemistry, Mettu University, P.O. BOX 318, Mettu, Ethiopia
4. Department of Chemistry, Haramaya University, P.O. BOX 138, Dire Dawa, Ethiopia