1. Department of Geology, Chukwuemeka Odumegwu Ojukwu University, Uli, Anambra State, Nigeria
2. Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka, Enugu State, Nigeria
3. Department of Geology, University of Calabar, P.M.B. 1115, Calabar, Cross River State, Nigeria
4. Central Science Laboratory, University of Nigeria, Nsukka, Enugu State, Nigeria
5. Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria