[1] Univ Bamenda, Dept Chem, Fac Sci, POB 39, Bambili, Bamenda, Cameroon
[2] Univ Bamenda, Higher Teacher Training Coll, Dept Chem, POB 39, Bambili, Bamenda, Cameroon
[3] Univ Bamenda, Natl Higher Polytech Inst, Dept Chem & Biol Engn, POB 39, Bambili, Bamenda, Cameroon
[4] Univ Buea, Dept Chem, Fac Sci, POB 63, Buea, Cameroon
[5] Univ Bamenda, Dept Fundamental Sci, Higher Tech Teachers Training Coll, POB 39, Bambili, Bamenda, Cameroon
[6] Univ Yaounde I, Dept Inorgan Chem, Fac Sci, POB 812, Yaounde, Cameroon