A simple and sensitive reversed phase high performance liquid chromatographic (HPLC) method was developed for the determination of biomolecules in different types of tea. Most of the High Performance Liquid Chromatography (HPLC) methods used for the determination of tea biochemicals include gradient elution systems which involve expensive instrumentation. The aim of this study was to develop an improved sensitive, fast, cost effective and accurate isocratic HPLC method with photo diode array (PDA) detection for analysis of Gallic acid, caffeine and catechins in tea, using a suitable internal standard. The developed HPLC analytical method consisted of a C 6phenyl column and an isocratic elution system of Water: acetonitrile: methanol: ortho phosphoric acid: ethyl acetate (77.5:18:2.0:0.5:2.0 v/v/v/v/v) at a flow rate of 1.0 mL/min. The detection wavelength was chosen at 278 nm with guaiacol (2-methoxyphenol) used as an internal standard as it did not co-elute with the analytes of interest. Statistical comparison of the analytical result obtained for gallic acid, caffeine and catechins in four tea types-green CTC (cut, tear and curl), black CTC, green orthodox and black orthodox using the developed method and ISO 1405-2:2005(E) method did not show significant difference. The method was validated and showed consistency to qualitative and quantitative determination of the tea biomolecules of interest.

Chlorogenic acid (CGA) one of tea biomolecules is a natural antioxidant that neutralizes free radicals in the body. It has also anti-obesity, anti-atherosclerotic and anti-cancer properties. Gallic acid exists in form of free acids and esters in plant material. This ubiquitous chemical is one of the many biologically active phenolic compounds of plant origin. Theanine a non-protein amino acid also called L-theanine is speculated to increase the levels of GABA, serotonin and dopamine. It has been used as a nutritional supplement in reducing stress, causing feelings of relaxation and improved mood. The aim of this study was to determine the variation of the levels of CGA, GA and theanine with processing technologies. Six tea cultivars TRFK 6/8, TRFK 11/4, TRFK 12/2, TRFK 31/8, TRFK 54/40 and TRFK 306/1 were selected for use in the study. Their leaf was processed to obtain CTC and orthodox tea products with green and black tea types being made. Profiling was done using High Performance Liquid Chromatography (Shimadzu Japan) equipped with photo-diode array detector (SPD-M20A). Graphical representation of the mean levels of Chlorogenic acid, Gallic acid and L-theanine contents was done using Microsoft® Excel, version 2010. Standard error of the mean was used to determine levels of significant differences.The result showed that TRFK 306/1 had the highest levels of CGA for both CTC and orthodox processing techniques while TRFK 12/2 had the lowest levels. In general, the levels were higher in black teas than in the green tea types. The levels of GA were in the range of 0.28-0.51% in green teas and 0.28-0.55% for the black tea types. At the cultivars level, black teas had significantly high levels of GA than the green teas. The theanine levels ranged at 0.97-1.87% for green teas and 0.79-1.47% for the black tea types.