Table 5. Detection limits of glycopeptides, carbohydrates, and phosphopeptides using 3-AQ/CA, 3-AQ/CHCA, and 2,5-DHB.a) [Reproduced from ref. 14 with Copyright permission of American Chemical Society.].
| No. | Name | Detection limit (fmol/well) | |||||
|---|---|---|---|---|---|---|---|
| [M+H]+ | [M−H]− | ||||||
| 3-AQ/CA | 3-AQ/CHCA | 2,5-DHB | 3-AQ/CA | 3-AQ/CHCA | 2,5-DHB | ||
| Glycopeptides | |||||||
| Sialoglycopeptides | |||||||
| 1 | Transferrin GP1 | 10 | 10 | 100 | 1 | 1 | 10 |
| 2 | Transferrin GP2 | 10 | 100 | 100 | 10 | 10 | 100 |
| 3 | Fetuin GP1 | 10 | 100 | 100 | 10 | 10 | 100 |
| 4 | Fetuin GP2 | 100 | 100 | 1000 | 10 | 100 | 100 |
| 5 | Fetuin GP3 | 1000 | — | — | 100 | 1000 | — |
| Asialoglycopeptides | |||||||
| 6 | Asialotransferrin GP1 | 1 | 1 | 1 | 1 | 1 | 1 |
| 7 | Asialotransferrin GP2 | 1 | 1 | 1 | 1 | 1 | 10 |
| 8 | Asialofetuin GP1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 1 |
| 9 | Asialofetuin GP2 | 0.01 | 0.1 | 0.1 | 0.1 | 0.1 | 1 |
| 10 | Asialofetuin GP3 | 0.1 | 1 | 10 | 0.1 | 1 | 10 |
| Carbohydrates | |||||||
| Sialoglycans | |||||||
| 11 | A1 glycan | 1 | 1 | 100 | 0.1 | 0.1 | 100 |
| 12 | A2 glycan | 1 | 1 | 100 | 1 | 1 | 100 |
| Neutral glycans | |||||||
| 13 | NA2 glycan | 0.1 | 1 | 1 | 1 | 1 | 10 |
| 14 | NA4 glycan | 1 | 1 | 10 | 1 | 1 | 10 |
| Phosphopeptides | |||||||
| 15 | β-Casein 33–48 | 1 | 1 | 1 | 1 | 1 | 1 |
| 16 | β-Casein 1–25 | 1 | 1 | 10 | 1 | 1 | 10 |
a) The detection limit for glycopeptides, carbohydrates, and phosphopeptides using 3-AQ/CA, 3-AQ/CHCA, and 2,5-DHB in positive- and negative-ion modes. The detection limit was defined as the lowest quantity of analyte detected as [M+H]+ or [M−H]− with S/N>2 within an error ratio of 25% at different concentrations made by 10-fold serial dilutions. “—” indicates that no ions were detected for that analyte at ≤1000 fmol.