Table 2.
Gradient elution and valve switching programs.
| SPE Pump (Left Pump) | Analytical Pump (Right Pump) | Valve | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Time (min) | Flow rate (mL/min) | Solvent A a (%) | Solvent B b (%) | Time (min) | Flow Rate (mL/min) | Solvent A a (%) | Solvent B b (%) | Switch Time (min) | Valve State |
| 0 | 1 | 100 | 0 | 0 | 1 | 85 | 15 | 0 | 1-2 |
| 0.5 | 1 | 85 | 15 | 5 | 1 | 85 | 15 | 0.5 | 6-1 |
| 1 | 0.3 | 10 | 90 | 15 | 1 | 80 | 20 | 1 | 1-2 |
| 25 | 0.3 | 10 | 90 | 20 | 1 | 70 | 30 | ||
| 26 | 1 | 100 | 0 | 25 | 1 | 70 | 30 | ||
| 30 | 1 | 100 | 0 | 25.1 | 1 | 85 | 15 | ||
| 30 | 1 | 85 | 15 | ||||||
a water, containing 0.4% acetic acid and 25 mM ammonium acetate; b acetonitrile.