Table 6.
LC/MS-MS parameters for the API 3000 triple quadrupole mass spectrometer
| Mass Spectrometer Parameters | dX | dI | dU | 8-oxo-dG |
|---|---|---|---|---|
| 14N Q1→Q3 m/z1 | 269→153 | 253→137 | 229→113 | 284→168 |
| 15N Q1→Q3 m/z | 273→157 | 257→141 | 231→115 | 289→173 |
| Nebulizer gas (psi)) | 8 | 8 | 8 | 8 |
| Curtain gas (L/min) | 8 | 8 | 8 | 8 |
| Collision gas (L/min) | 6 | 4 | 4 | 8 |
| Ion Spray Voltage (V) | 4000 | 4500 | 4500 | 4000 |
| Temperature (°C) | 400 | 350 | 350 | 400 |
| Turbo ion spray gas (psi) | 800 | 800 | 400 | 800 |
| Declustering potential (V) | 20 | 20 | 20 | 20 |
| Focusing potential (V) | 100 | 100 | 100 | 100 |
| Entrance potential (V) | 5 | 5 | 5 | 5 |
| Collision Energy (V) | 10 | 10 | 10 | 20 |
| Collision cell exit potential (V) | 10 | 10 | 10 | 10 |
| HPLC Parameters2 | dX | dI | dU | 8-oxo-dG |
| %Solvent B | 1.3 | 0.7 | 1 | 1.5 |
| Retention time (min)3 | 8-10 | 10-12 | 3-5 | 11-13 |
1
m/z values monitored in MRM mode for the transition of the parent ion to the fragment ion; 14N refers to the analyte under study; 15N refers to the isotopically labeled internal standard.
2
Thermo Hypersil Gold C18 column used in step 39
3
Retention time is expected to range over the values indicated