An investigation in the use of HPLC with UV and MS-electrospray detection for the quantification of tea catechins

A rapid RP-HPLC method was applied to the analysis of a green tea extract (GTE). The use of a C-18 column with an internal diameter (ID) of 3.0 mm was compared with a similar one of 4.6 mm ID. Catechins quantification was performed both by ultra violet diode array detection (UV-DAD) and atmospheric pressure electrospray ionization-mass spectroscopy (API-ES-MS). Some statistical data were pointed out. High precision degree on the migration times was obtained: percent relative standard deviation lower than 0.7% was achieved by both the two detection systems. Advantages of mass detection were found to be the higher specificity and sensitivity of the signal, counterbalanced by stability of the UV-DAD signal over a significantly longer period. In fact, even if similar precision results on the quantification of green tea catechins between UV and MS detections have been found, the MS detection system was less accurate and provided less stable detector response. Finally, performance of narrower HPLC columns was evaluated in terms of detection limits: the 3.0 mm ID-column LODs of catechins were one order of magnitude lower than those of the 4.6 mm ID-column.