Abstract: An analytical method for simultaneous determination of phenolic acid compounds (free phenolic acids, free phenolic acid esters, bound phenolic acids, soluble phenolic acid glycosides and insoluble phenolic acid glycosides) in tea samples was established by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The free phenolic acids in samples were extracted with 70% methanol, and the extract was hydrolyzed with 2 mol/L NaOH solution (containing 1 g/100 mL ascorbic acid and 10 mmol/L EDTA) and 1 mol/L HCl solution, separately, to release free phenolic acid esters and soluble phenolic acid glycosides, respectively. The reside after extraction was hydrolyzed by alkali and acid, separately, to release bound phenolic acid and insoluble phenolic acid glycosides. The calibration curves for the 23 phenolic acid compounds showed good linearity in the range of 50–1 000 μg/L, with correlation coefficients (r) higher than 0.996, and the relative standard deviation was less than 8.84%. The recoveries of free phenolic acids in tea samples were 71.14%–105.43%, and the recoveries of free phenolic acid esters and soluble phenolic acid glycosides were 82.81%–108.93% and 39.09%–102.25%, respectively. Fourteen phenolic acid compounds were identified in tea, with a total content ranging from 7.84 to 12.90 mg/g.

Key words: ultra-high performance liquid chromatography-tandem mass spectrometry; phenolic acids; tea