ISOLATION OF CAFFEINE FROM TEA BAGS
*Jindal Diksha, Singh Jarnail, Patil R.K. and Patil H.C.
Caffeine extracted and characterized from tea bags. Isolation was done by liquid-liquid extraction method. The extraction was done in four steps: steeping, evaporation, liquid-liquid extraction and distillation. Here the organic solvent dichloromethane is used to extract caffeine from an aqueous extract of tea leaves because caffeine is more soluble in dichloromethane (140 mg/ml) than it is in water (22 mg/ml). Calcium hydroxide is added to the extraction medium to ensure that the acidic components in the tea bags remain water soluble and that caffeine is the free base. However, the tannins that are slightly soluble in dichloromethane can be eliminated by converting it to their salts (phenolic anions by adding sodium carbonate) (tannins are phenolic compounds of high molecular weight and being acidic in nature can be converted to salts by deprotonation of the -OH group) which remain in the water. The technique used for purity analysis was done using melting point analysis. The melting point of caffeine extracted from tea bags was found to be 238Â°C. The purity showed that the results that the extracted caffeine was 90% pure.
Keywords: Caffiene, Xanthine alkaloids, Dichloromethane, tea bags, Melting point.
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