Determination of Caffeine in Coffee Using Uv/Vis Spectrophotometry
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Date
2009-07
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Addis Ababa Universty
Abstract
Spectrophotometric method was developed for the determination of the amount of caffeine in
coffee samples. The Uv/vis spectra of pure caffeine in water and dichloromethane were obtained
with peak absorption at λmax 271 and 275 nm, respectively. The developed method showed
linearity for the determination of caffeine in the range of 2.5x10-5 mol dm-3 to 1.25x10-4 mol dm-3.
The method also showed good precision, accuracy with limits of detection 2.14 and 1.79 mg/l in
water and dichloromethane, respectively. The relative standard deviation for the determination of
a 2.0x10-5 mol dm-3 caffeine was 4.53% and 3.72% (n=5) in water and dichloromethane,
respectively. The molar decadic absorption coefficients of caffeine in water and dichloromethane
at maximum wavelength are 1031.2+0.036 and 1004.4+0.029 m2 mol-1, respectively. Analytical
parameters were investigated primarily; the method was applied to quantify the amount of
caffeine in coffee samples. The method was found to be fast, simple, cost effective and
environmental friendly for the determination of caffeine in aqueous solution coffee samples with
satisfactory results.
Keywords: Coffee Arabica, Caffeine, Absorbance, Uv/vis spectrophotometry, Extraction
Description
Keywords
Coffee Arabica, Caffeine, Absorbance, Uv/vis spectrophotometry, Extraction