Analysis of theaflavins in biological fluids using liquid chromatography–electrospray mass spectrometry

A HPLC–MS procedure for the sensitive and specific analysis of the black tea flavonoid theaflavin in human plasma and urine was developed. Levels were measured after enzymatic deconjugation, extraction into ethyl acetate, and separation by HPLC, using tandem mass spectrometry as a detecting system. Two healthy volunteers consumed 700 mg theaflavins, equivalent to about 30 cups of black tea. The maximum concentration detected in blood plasma was 1.0 μg l−1 in a sample collected after 2 h. The concentration in urine also peaked after 2 h at 4.2 μg l−1. Hence, only minute amounts of theaflavins can be detected in plasma and urine samples of healthy volunteers after ingestion.