Extraction of Caffeine from Tea leaves
Isolation, purification and characterization of alkaloid caffeine from tea leaves
Date Submitted: September 3, 2014
Abstract
Caffeine is one of the main constituents of tea leaves. In this experiment, 0.0039 g of pure caffeine was isolated from tea leaves. This was done through solid-liquid extraction followed by multiple liquid-liquid extraction. Then crude material obtained was then purified by sublimation. The isolated caffeine was subjected to thin layer chromatography (TLC) together with a standard caffeine. The Rf value obtained for both isolated caffeine and standard caffeine was 0.24.
Keywords: solid-liquid extraction, multiple liquid-liquid extraction, sublimation, thin layer chromatography, percent caffeine
Introduction
Many organic compounds are obtained from natural sources through isolation. In this experiment, caffeine is isolated from tea leaves. Caffeine belongs to a class of organic compounds isolated from plants called alkaloids. These nitrogenous compounds contain molecule that has purine ring system that plays an important role in living systems. Caffeine is one of the most widely used stimulants.It can increase the person 's alertness, reduce drowsiness and fatigue. It also affects the blood circulation because the heart is stimulated thus, making the blood vessels relaxed (vasodilation). In addition, it also acts as diuretic. Caffeine constitutes as much as 5% by weight of tea leaves. Caffeine is also the natural constituent of coffee which contains less than 135 mg per cup and cola which contains 3.75 mg per ounce.
Tea leaves are not composed of caffeine alone. Tannins, cellulose, small amount of glucose, free amino acids, some proteins, residual pigments and saponins are compounds extracted along with caffeine into the tea. Cellulose is the main component of tea leaves and is insoluble in water. Tannins are phenolic compounds with high molecular weight, acidic behavior and soluble in water. Caffeine, like
Date Submitted: September 3, 2014
Abstract
Caffeine is one of the main constituents of tea leaves. In this experiment, 0.0039 g of pure caffeine was isolated from tea leaves. This was done through solid-liquid extraction followed by multiple liquid-liquid extraction. Then crude material obtained was then purified by sublimation. The isolated caffeine was subjected to thin layer chromatography (TLC) together with a standard caffeine. The Rf value obtained for both isolated caffeine and standard caffeine was 0.24.
Keywords: solid-liquid extraction, multiple liquid-liquid extraction, sublimation, thin layer chromatography, percent caffeine
Introduction
Many organic compounds are obtained from natural sources through isolation. In this experiment, caffeine is isolated from tea leaves. Caffeine belongs to a class of organic compounds isolated from plants called alkaloids. These nitrogenous compounds contain molecule that has purine ring system that plays an important role in living systems. Caffeine is one of the most widely used stimulants.It can increase the person 's alertness, reduce drowsiness and fatigue. It also affects the blood circulation because the heart is stimulated thus, making the blood vessels relaxed (vasodilation). In addition, it also acts as diuretic. Caffeine constitutes as much as 5% by weight of tea leaves. Caffeine is also the natural constituent of coffee which contains less than 135 mg per cup and cola which contains 3.75 mg per ounce.
Tea leaves are not composed of caffeine alone. Tannins, cellulose, small amount of glucose, free amino acids, some proteins, residual pigments and saponins are compounds extracted along with caffeine into the tea. Cellulose is the main component of tea leaves and is insoluble in water. Tannins are phenolic compounds with high molecular weight, acidic behavior and soluble in water. Caffeine, like
References: [1] Battelheim, F.A. & Landesberg, J. (2001). Laboratory experiments for Organic and Biochemistry, 4th ed. USA: Hardcourt, Inc. [2] Extraction of caffeine from tea leaves. Retrieved August 2013 from: http://spot.pcc.edu/~chandy/241/CaffeineExtractionCH2CCl2.pdf [3] Pavia, P.L...(et. al). (2005). Introduction to Organic laboratory techniques, 2nd ed. Belmont, CA: Thomson Learning, Inc. [4] Palleros, D.R. (2000). Experimental Organic Chemistry. USA: John Wiley & Sons, Inc.