Spectrophotometric method for the quantitative determination of caffeine in the hulls of ripe tea seeds

Abstract

Determination Procedure. In a round-bottomed flask, i0 g of comminuted hulls was extracted five time with hot water (S/L = i:i0) in the boiling water bath for 60 min, after which the extract was filtered through a suction filter. In a 100-ml separatory funnel, 5 ml of aqueous extract was treated with 5 ml of a solution of sodium phosphate buffer having pH 8.6, and the caffeine was extracted with chloroform (3 × 25 ml). The chloroform extracts were filtered into a 100-ml measuring flask through a layer (3 g) of anhydrous sodium sulfate previously moistened with chloroform. The sulfate on the filter was washed with small portions of chloroform which were added to the main extract, and the volume was made up to the mark with chloroform. The optical density was determined on a SF-26 instrument at 273 nm in a cell with a layer thickness of i cm. The amount of caffeine (X, %) was calculated from the formula: