Introduction: Caffeine is one of the constituent which generally found in Diet 3 in 1 instant coffee
products. These products were commercially sold in Muang District, KhonKaenProvince so the aim of this study
was to determine the amount of caffeine in these products. Materials and Methods: A simple HPLC method was
applied to determine the amount of caffeine in these products. Liquid-liquid extraction was used for the extraction
of caffeine from these samples. HPLC separation was carried out using Hypersil ODS C18 column and detected
at wavelength 254 nm. This chromatographic condition using the mixture of methanol and water with constant ratio
at 65:35 was found to complete resolution of caffeine. This HPLC method was validated in the topics of specificity,
accuracy, precision, linearity, limit of detection and limit of quantitation and could give reliable results. Results:
From the result of this study, the amount of caffeine in these products was found from 37 mg to 107 mg per pack
which can cause health problem for over consumption of these products. Conclusion: Therefore, the awareness
of consumption these products should be provided for the people who would like to use these products for the diet
and weight control purpose to protect from the adverse side effect from caffeine overdose.