Fast gradient HPLC/MS separation of phenolics in green tea to monitor their degradation

- Fast gradient HPLC/MS separation of phenolics in green tea was developed.
- The degradation of catechins and other phenolics were monitored.
- Antioxidant capacity is independent of the duration of green tea infusion.
- The content of catechins already rapidly decreases after 3 weeks of storage.
- The classification of green teas was performed using multivariate data treatment.

The degradation of catechins and other phenolics in green tea infusions were monitored using fast HPLC/MS separation. The final separation was performed within 2.5 min using Ascentis Express C18 column (50 mm × 2.1 mm i.d.) packed with 2 μm porous shell particles. Degradation was studied in relation to the temperature of water (70, 80, 90 °C) and the standing time of the infusion (up to 6 h). Along with chromatographic separation, the antioxidant properties of the infusions were monitored using two spectrophotometric methods. During staying of green tea infusion, the degradation of some catechins probably to gallic acid was observed. Finally, the influence of tea bag storage on antioxidant properties of green tea was evaluated. Rapid degradation of antioxidants after 3 weeks was observed. The principal component analysis, factor analysis and discriminant analysis were used for the statistical evaluation of obtained experimental data.