Table 2.
HPLC-DAD and HPLC-ESI-MS results of the extractable and esterified phenolic compounds found in the sunflower seed hull powder (SP).
| Phenolic compound | Peak number | mg/100 g | Retention time (min) | HPLC-UV-DAD λmax (nm) | HPLC-ESI-MS/MS [M-H]− (m/z) |
|---|---|---|---|---|---|
| Extractable phenolic compounds | |||||
| Monoacyl quinic acids | |||||
| O-Caffeoylquinic acid | 1 | 3.0 ± 0.8 | 10 | 327 | 353 |
| O-Caffeoylquinic acid isomer | 2 | 23.7 ± 0.8 | 19.5 | 326 | 353, 191, 179 |
| Diacyl quinic acids | |||||
| Caffeoyl-dimethoxycinnamoylquinic acid | 3 | 2.2 ± 0.3 | 28.2 | 329 | 543, 381 |
| Caffeoyl-dimethoxycinnamoylquinic acid isomer | 4 | 1.6 ± 0.4 | 29.3 | 329 | 543, 381 |
| Dicaffeoylquinic acid | 5 | 0.9 ± 0.7 | 30.3 | 321 | 515, 353, 179 |
| Total content of extractable phenolics | 31.4 | ||||
| Esterified phenolic compounds | |||||
| Ferulic acid monomers | 6 | 34.0 ± 0.7 | 33 | 244/323 | 193 |
| Ferulic acid dimers | 7 | 3.5 ± 0.5 | 44 | 245/322 | 385 |
| Ferulic acid trimers | 8 | 15.4 ± 0.8 | 66 | 327 | 563 |
| Total content of non-extractable (esterified) phenolics | 52.9 |