Browsing by Author "Getinet, Yirga"

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    Square Wave Voltammetric Determination of Caffeine in Coffee
    (Addis Ababa Universty, 2005-07) Getinet, Yirga; Tessema, Merid (PhD)
    A carbon paste electrode was utilized for monitoring caffeine using square wave voltammetry (SWV). This method was applied to determine the caffeine levels in some coffee samples. Optimal experimental conditions for the analysis were found to be as follows: pH value of 6 for the suporting electrolyte, SW frequency of 30 Hz, SW amplitude of 40 mV, and step potential of 7 mV. Having these optimum conditions a linear range was observed with in the concentration of 0 ~ 250 mg/L. For caffeine concentration of 50 mg/L, the detection limit three times the standard deviation in measured concentration (n=6) was found to be (10.67μg/mL). This method was applied for the determination of the caffeine levels in Ethiopian green coffee samples. The caffeine content of Ethiopian green coffee samples ranged from 0.9 - 1.16 % on dry mass basis. The quantities are in good agreement with those reported in the literature for Coffea arabica. The results are also in good agreement with values determined by HPLC method. Key words: Square Wave Voltammetry, Coffee, Caffeine and Carbon Paste Electrode