1. Fossil Fuels and Environmental Geochemistry, Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria
2. Department of Geology, Obafemi Awolowo University, Ile-Ife, Nigeria
3. Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
4. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Wushan, P. R. China