Table 1.
Summary of diagnostic ions generated by LDI-TOF MS/MS analysis of reference standards. The corresponding spectra can be found in the ESM along with the structures of the secondary plant metabolites
| Reference standard | Molecular formula | Negative ion mode | Positive ion mode | ||
|---|---|---|---|---|---|
| Detected ion (m/z) | Main fragment ions | Detected ion (m/z) | Main fragment ions | ||
| 3-Dehydroquinic acid | C7H10O6 | [M−H]−189 | 169, 125, 85 | [M+Na]+213 | 211, 193, 180, 154, 124 |
| Quinic acid | C7H12O6 | [M−H]− 191 | 171, 125, 83 | [M+Na]+215 | 213, 211, 193, 180, 154, 124 |
| Apigenin | C15H10O5 | [M−H]− 269 | 225, 201, 151 | [M+H]+271 | 271, 152, 118 |
| Luteolin | C15H10O6 | [M−H]− 285 | 241, 217, 199, 175, 151, 134 | [M+Na]+309 | 279, 250, 97, 68 |
| Tricina | C17H14O7 | [M−H]− 329 | 314, 298, 284, 150 | [M+H]+331 | 315, 301, 286, 270, 239, 178, 153 |
| Rosmarinic acid | C18H16O8 | [M−H]− 359 | 271, 197, 179, 161, 134 | [M+Na]+383 | 381, 363, 337, 307, 219, 201, 183 |
aTricin is an in-source decay (ISD) product of the reference standard tricin-5-glycoside. Due to deviation in the mass accuracy, it is not considered as tentatively identified by LDI-TOF MS/MS