Study of extraction and HPTLC - UV method for estimation of caffeine in marketed tea (Camellia sinensis) granules

Abstract

A simple, precise and accurate high-performance thin-layer chromatographic (HPTLC) method has been established and validated for screening and quantitative estimation of caffeine in different extracts of tea samples (Camellia sinenesis). Separation was performed on silica gel 60 F254 HPTLC plates with ethyl acetate:methanol in the proportion of 27: 3 (v/v), as a mobile phase. The determination was carried out in the ultraviolet (UV) region using the densitometric remission-absorbance mode at 274 nm. Maximum recovery of caffeine was achieved when extracted with 5% diethyl amine in DM water (v/v). The maximum concentration of caffeine in tea samples was found to be 2.145%, dry weight basis. Caffeine response was found to be linear over the range of 2-14 μg per zone. Limits of detection and quantitation were found to be 40 and 120 ng/spot, respectively. The HPTLC method was validated in terms of precision, accuracy, sensitivity and robustness. Some rare parameters for the HPTLC method like calculation of flow constant (k) and plate efficiency (N) are included specially. Key words: Caffeine, Camellia sinensis, HPTLC - UV method, theaceae, tea granules