1. Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Nigeria
2. Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka, Nigeria
3. Department of Geology, Chukwuemeka Odumegwu Ojukwu University, Anambra, Nigeria
4. Department of Geology, University of Calabar, Calabar, Nigeria
5. Central Science Laboratory, University of Nigeria, Nsukka, Nigeria