DETERMINATION OF CAFFEINE IN TEA PRODUCTS BY AN IMPROVED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY METHOD

At present, the commonly used HPLC method for the analysis of caffeine content in tea brews employs direct application of the samples on the column. This practice gradually reduces the efficiency of the column and shortens its life. In the modified method, the interfering tea pig ments are effectively removed by passing the sample through a Sep-Pak C-18 cartridge. Then its injection on a reversed phase mu-Bondapak C-1 8 column employing acetonitrile and water (20:80 v/v) as mobile phase reduces the analysis time without affecting either the resolution of t he peaks or the accuracy of caffeine determination. This method is sho wn to estimate accurately soluble caffeine contents in the brews of bl ack tea, decaffeinated tea, and decaffeinated instant tea samples. Thu s, the method is ideally suited for rapid routine analysis of black te a and its products.