Table 1.
Retention time (tR), retention factor (k), separation factor (α), peak purity (PP), absorption wavelength and mass spectra data of catechins in Oolong tea leaf waste extract.
| Peak No. | Compound | tR | k | α | PP (%) | Absorption Wavelength (λmax, nm) | Mass Spectra ([M − H]−, m/z) d | Tandem Mass Fragment Ions (MS2) | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Extract c | Standard | Reported | Extract | Standard | Reported | Extract | Reported | ||||||
| IS a | L-tryptophan | 5.11 | - | - | - | - | - | - | - | - | - | - | - |
| 1 | epigallocatechin (EGC) | 7.40 | 1.26 | 2.08 (1,2) b | 99.95 | 270 | 270 | 271 e | 305 | 305 | 305 e | 261, 219, 137 | 261, 219 h, 137 g |
| 2 | epicatechin (EC) | 11.88 | 2.63 | 2.08 (1,2) b | 99.94 | 278 | 278 | 275 f | 289 | 289 | 289 f | 245, 203, 125 | 245, 203, 125 i |
| 3 | epigallocatechin gallate (EGCG) | 12.72 | 2.89 | 1.10 (2,3) b | 99.98 | 274 | 274 | 274 e | 457 | 457 | 457 e | 331, 305, 169, 125 | 331, 305, 169 i, 125 g |
| 4 | gallocatechin gallate (GCG) | 13.86 | 3.24 | 1.12 (3,4) b | 99.92 | 274 | 274 | 274 e | 457 | 457 | 457 e | 305, 169, 125 | 305, 169, 125 g |
| 5 | epicatechin gallate (ECG) | 16.42 | 4.03 | 1.24 (4,5) b | 99.99 | 276 | 278 | 278 e | 441 | 441 | 441 e | 289, 169 | 289, 169 h |
a IS = internal standard. b Numbers in parentheses represent values between two neighboring peaks. c A gradient mobile phase of acetonitrile and 0.1% formic acid in water was used. d Determined by LC-MS. e Based on a reference by Tsai and Chen [6]. f Based on a reference by Wu, Xu, Héritier and Andlauer [11]. g Based on a reference by Wang, Li, Wang, Li, Ling, Liu, Chen and Bi [2]. h Based on a reference by Rio, Stewart, Mullen, Burns, Lean, Brighenti and Crozier [12]. I Based on a reference by Bastos, Saldanha, Catharino, Sawaya, Cunha, Carvalho and Eberlin [13].