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Background: There are reports of abuse and toxicity resulting from taking caffeine, a psychoactive stimulant derived from various products like tea, which is known to increase alertness and elevate mood but prone to addiction.

Objectives: This study was aimed at determination of the caffeine content of green, herbal, and black tea samples sourced from supermarkets in Sagamu, south-west Nigeria by chemical and HPLC technique.

Methods: Chemical analysis was by precipitation, filtration followed by organic solvent extraction while the HPLC is equipped with a reverse phase C18 column, detection wavelength of 272 nm and run with a mobile phase of water: methanol (30:70% v/v).

Results: Caffeine eluted at about 1.58 mins to 1.65 mins. The calibration graph for the HPLC method was linear within the range of 10-100 μg/ml (R2 = 0.9997) with the regression equation of y=73.88x-25.96. Percentage (%) caffeine by chemical analysis ranged from 0.13±0.01 to 1.72±0.13; and by h.p.l.c from 0.14±0.192 to 0.85±0.025 while caffeine content was below detection limit in two samples, (D, and I); where sample D had the lowest caffeine content by chemical method but undetectable by the h.p.l.c method. However, sample F had 0.66±0.20 by the chemical method but gave the lowest caffeine content of 0.14±0.192 by the h.p.l.c method. There was statistically significant difference between the mean results of the two methods (t=4.931, p < 0.05).

Conclusion: All tea samples contained caffeine in amounts that are low and safe, and that meets with regulatory specifications such as the US FDA. This has positive implications for public health and quality control of the tea samples.

Keywords: Caffeine, chemical analysis, HPLC, herbal tea, green tea, black tea.