EXTRACTION, IDENTIFICATION AND ESTIMATION OF CAFFEINE IN GREEN AND BLACK TEA SAMPLES BY A SIMPLE UV-VISIBLE SPECTROSCOPIC METHOD

Abstract

Caffeine is a widely consumed psychoactive compound present in coffee, tea, soft drinks, energy drinks, and chocolates. It is a diuretic and a central nervous system (CNS) stimulant. Apart from stimulating the CNS, it exerts beneficial effects in combination with other substances like L-theanine and catechins. Caffeine was extracted from green tea and black tea samples using various solvents. The maximum yield of caffeine was obtained from dichloromethane extracts. The extracted caffeine was identified by TLC and FTIR. A simple UV spectroscopic method was developed and validated for the estimation of caffeine in green tea and black tea. The wavelength maximum of caffeine was obtained at 272 nm in distilled water. The Beer-Lambert law was obeyed in the concentration range of 0.5 to 35 µg mL-1 for caffeine. The linearity, accuracy, precision, robustness, and ruggedness, limit of detection and limit of quantification of this method are within the limits of ICH guidelines. This method was found to be precise as % RSD was less than two. The LOD and LOQ values were 0.03 µg mL-1 and 0.091 µg mL-1,respectively. The percentage purity of caffeine from green tea and black tea samples was found to be 98.32% and 99.42 %. Thus, the proposed method was found to be rapid, specific, precise and accurate for the routine analysis of caffeine in green and black tea samples.