Capillary liquid chromatography/electrospray mass spectrometry for the separation and detection of catechins in green tea and human plasma

The separation and detection of biologically active green tea catechins has been accomplished using capillary liquid chromatography/electrospray mass spectrometry (cLC/ESI-MS). Microscale determination (~ 20 ng) of all six catechins in a green tea infusion, and the most extensively studied catechin, (-)epigallocatechin gallate (EGCG), in human plasma is demonstrated by cLC/ESI-MS with selected ion monitoring of protonated molecular ions. The overall quality of the analysis is shown to be dependent on the use of a capillary column with a deactivated, monomeric C₁₈ stationary phase. The high chromatographic separation efficiency of this packed-capillary column, combined with the high sensitivity and selectivity afforded by the mass spectrometer as detector, provide a tellable approach to the analysis of picomolar quantities of these interesting compounds in complex matrices.