E. B. Mubofu
University of Dar es Salaam
United Republic of Tanzania

P.O. Box 35061, Dar es Salaam, Tanzania

S. Mlowe
University of Dar es Salaam; University of Zululand
United Republic of Tanzania

Chemistry Department, University of Dar es Salaam; Chemistry Department, University of Zululand,

P.O. Box 35061, Dar es Salaam, Tanzania;
Private Bag X1001, KwaDlangezwa, 3886, South Africa

N. Revaprasadu
University of Zululand
South Africa

Chemistry Department

Private Bag X1001, KwaDlangezwa, 3886