CoA for Green Tea.
Characterization of Material Study
|Compound measured||Measurement||Value||Study sequence||Additional information||N replicates|
China Green Tips, varietal
For product extraction, 200 mg of sample and 20 mL methanol were added to a 20 mL scintillation vial. Mixtures were shaken overnight at room temperature, filtered, and dried under reduced pressure and stored at -80°C until analysis.
JEOL ECA-400 spectrometer
Each sample was resuspended in CD3OD to a concentration of 10 mg/mL. NMR spectra were acquired with a JEOL ECA-400 spectrometer equipped with a high-sensitivity JEOL Royal probe and a 24-slot autosampler. NMR chemical shift values were referenced to residual solvent signals for CD3OD (δH 3.31 ppm).
Q Exactive Plus quadrupole-orbitrap mass spectrometer
Full scan, high resolution
Electrospray ionization (ESI)
Waters Acquity UPLC
95:5 (A:B) for 1 min, then gradient to 0:100 over 20 minutes, holding for 1 min at 0:100
Waters Acquity UPLC BEH C18 1.7 μm, 2.1 × 50 mm
The mass spectrometer was operated in the positive/negative switching ionization mode over a full scan range of m/z 150-2000 with the following settings: capillary voltage, 5 V; capillary temperature, 300 °C; tube lens offset, 35 V; spray voltage, 3.80 kV; sheath gas flow 35 and auxiliary gas flow 20.
Quantification of the major catechin, phenolic acid, and flavonoid components of the green tea products used 15 calibration standards. LC-MS analysis was conducted as described. Standards were prepared in spectrometric-grade MeOH and diluted in a two-fold dilution series ranging from 0.1-200 μg/mL before injection. A calibration curve was constructed by plotting the area of the selected ion chromatogram for each standard versus nominal concentration. Concentrations of each standard in the extracts were determined by 1/x2 weighted least-squares linear regression.