Determination of Caffeine, the Active Ingredient in Different Coffee Drinks and its Characterization by FTIR/ATR and TGA/DTA

Mohammad A. Abdalla

In this article a special attention has been given to the use of FTIR/ATR, a unique accessoryof Fourier Transform Infra-red Spectroscopy. This technique uses attenuatedtotal reflectance accessory(ATR) as a sampling system for determinationand quantification ofcaffeine contentin coffeesamples at the wavenumber(cm^-1)of the pure caffeine spectrum selected between (1600-1700 cm^-1) where any possible traces ofchloroform does not show any absorption[1]. Attenuated Total Reflectance accessory represented a simple technique that requires a very little samplepreparation [2]. In order to reach a meaningful approach of sample characterization, Thermal Gravimetric Analysis (TGA) hasbeen included in the research to identify the thermal properties of coffee samples selected for the study[3].The targeted coffee samples represented the coffee samples consumed,particularly: Arabian coffee blend home-made, roasted coffee blend home-made,instant coffee bought from the market and pure caffeine analytical reagent bought from SigmaChemicals.