Rapid determination of theaflavins by HPLC with a new monolithic column

The quantitative determination of four theaflavin monomers by a rapid reversed-phase high performance liquid chromatographic method was developed. A new RP-18 end-capped column with particle size 2 µm and equilibrated to 35°C in a Shimadzu temperature controller module was used. Four theaflavin monomers were successfully separated in 8 min by the new strategy, comparing to 20–85 min by HPLC in the peer literature reports. Linear gradient elution: from 92% mobile phase A (v) to 76% mobile phase A (v) during early 3 min and then 92% mobile phase A (v) till 8 min at elution flow rate 1.5 ml/min. The limits of detection and quantification were in the range of 0.1–0.3 and 0.4–1.1 mg/l. Satisfactory recoveries of theaflavin, theaflavin-3-gallate, theaflavin-3’-gallate and theaflavin-3,3’-gallate were 97.5–102.6, 98.6–102.4, 99.6–105.4, and 95.5–105.4%, respectively. The new method was applied to quantitative analysis theaflavins of tea samples, including 10 black teas, 5 oolong teas, and 5 green teas. This method is suitable for the rapid, accurate and inexpensive quantitative analysis of theaflavins under the basic detection conditions of HPLC.