Browsing by Author "Belay Abebe"

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    Standard procedure to determine the Percentage of caffeine in coffee seeds by UV/Vis Spectrophotometer
    (Addis Ababa University, 2005-07) Belay Abebe; Asfaw Araya (PhD)
    In this work using UV/Vis spectrophotometer the electronic transition properties of caffeine are investigated. The molar decadic absorption coefficients of caffeine in water and dichloromethane are 1112 m2 mole'1, 1010 m2 mole'1 respectively obtained. From the experimental results the transitional dipole moment of caffeine in water 11.50 xlO'30 C m and in dichloromethane 10.8OxlO'30 C m respectively calculated . In addition, fast and simple methods are developed that enable to quantify the contents of caffeine in coffee seeds. The methods are extracting caffeine from coffee solution by dichloromethane and apply Gaussian fit to remove the possible interferences with the caffeine spectra . The results obtained using our teclmiques are compared with HPLC and found to be similar. The methods have a good application for identifying decaffeinated coffee seeds which are discovered in Ethiopia Key words: caffeine, extract, absorbance, UV/Vis spectrophotometer