Comparative FTIR Characterization of Caffeine Functional Groups in Different Varieties of Kola Nuts (Cola Acuminata and Cola Nitida)

Abstract

Transform Infrared (FTIR) spectroscopy was employed to investigate and compare the caffeine-related functional groups present in different varieties of kola nuts obtained from Oba, Anambra State, Nigeria. The kola nut varieties analyzed include White Hausa kola (Cola nitida), Red Hausa kola (Cola nitida), Four-lobed Igbo kola (Cola acuminata), and Common Igbo kola (Cola acuminata). FTIR spectra were recorded in the range of 4000–650 cm⁻¹ at a resolution of 4 cm⁻¹ using an ATR-FTIR technique, and the results were compared with a standard caffeine spectrum. Characteristic absorption bands corresponding to key caffeine functional groups such as C–H, C=C, C=O, C=N, and C–N were identified across all kola nut varieties, confirming the presence of caffeine. White kola and Common Igbo kola exhibited absorption bands most closely aligned with the standard caffeine spectrum, while Red kola showed minor frequency shifts. The Fourlobed Igbo kola displayed more pronounced deviations, particularly in the C–H stretching region, likely due to interactions with other phytochemical constituents. Overall, the study demonstrates that FTIR spectroscopy is an effective, rapid, and non-destructive technique for identifying and comparing caffeine functional groups in different kola nut varieties, while also revealing varietal differences influenced by their molecular environments.