Analysis Of Caffeine From Tea Leaves

Extraction of Caffeine from Tea leaves and determination of purity by Chromatography

Cyrene John Cruz, Ma. Katrina Cruz, Nathaniel Cedric Custodio*, Eric Vince Del Valle

Department of Biology, University of Santo Tomas, Manila Philippines

ABSTRACT: Caffeine was extracted from tea leaves by the process of extraction. 14.97g of tea leaves was boiled in 200 ml of water, and it was extracted 3 times with dichloromethane. The residue was collected and it was extracted using NaOH, the residue is dried with Anhydrous Sodium Sulfate and the weight was measured. The percent yield was computed by getting ratio of the weight of the isolated compound and the weight of the tea leaves. The percent yield was 1.52%.

INTRODUCTION:

In order to accomplish extraction of caffeine from tea, several methods should take place. First is a solid-liquid extraction must be done in order to get the solid product into the liquid solvent. Second is a liquid-liquid reaction to remove all impurities that are not needed. Third is to dry the compound to remove the traces of water. In order to get the percent yield of caffeine, compare the ratio between the weight of the isolated caffeine and the weight of the tea leaves and multiple it by 100. In order to determine the purity of the substance a process thin layer chromatography should take place that it should have the same behavior with the pure

Because tannins are acidic and can be converted to phenolic salts by deprotonation of the –OH group when a base is added, it is possible to separate the tannins from caffeine. During the 2nd extraction process, when dichloromethane was added to the solution 2 immiscible layers were formed which are a upper layer containing the aqueous solution and a lower layer containing the organic solution. Dichloromethane is denser than water The 2nd extraction process was done for 3 times to maximize the yield of caffeine. The separatory funnel was slowly swirled so that intractable emulsion would not be produced and the product recovery would not be reduced. After the 2nd extraction process the lower layer part of the mixture is collected and the upper layer is discarded which contained tannins and sugars which composed of monosaccharides glucose and fructose and a disaccharide sucrose. The second extracted compound now contains caffeine, chlorophyll with traces of gallic acid from the reaction of dichloromethane and