Table 1. Liquid chromatography conditions used for the On-line Solid-Phase Extraction liquid-chromatography tandem mass spectrometry analysis.
| Time (min) | Flow rate (mL/min) | FCV-12AH valve position | Mobile phase | ||
|---|---|---|---|---|---|
| Pump A | Pump B | ||||
| A-1 (%) | A-2 (%) | B (%) | |||
| 0.00 | 3.50 | A | 95 | 0 | 5 |
| 0.99 | 4.00 | A | 95 | 0 | 5 |
| 1.00 | 4.00 | A | 0 | 95 | 5 |
| 1.80 | 0.35 | A | 0 | 95 | 5 |
| 2.00 | 0.35 | B | 0 | 95 | 5 |
| 2.50 | 0.35 | B | 0 | 95 | 5 |
| 8.00 | 0.35 | B | 0 | 20 | 80 |
| 9.60 | 0.35 | B | 0 | 20 | 80 |
| 9.61 | 0.35 | B | 0 | 1 | 99 |
| 9.63 | 0.80 | B | 0 | 1 | 99 |
| 11.00 | 0.80 | A | 0 | 1 | 99 |
| 11.02 | 5.00 | A | 0 | 1 | 99 |
| 11.03 | 5.00 | A | 1 | 0 | 99 |
| 12.01 | 5.00 | A | 95 | 0 | 5 |
| 12.04 | 4.00 | A | 95 | 0 | 5 |
| 12.54 | 4.00 | A | 95 | 0 | 5 |
Valve position A: sample extraction or washing on the Solid-Phase Extraction column
Valve position B: back-flush onto the analytical column and chromatographic separation
Mobile phase A-1: 1.0 vol% formic acid
Mobile phase A-2: 0.05 vol% acetic acid
Mobile phase B: methanol
Pump C delivered 0.05 vol% acetic acid/methanol (95:5, v/v) at 0.35 mL/min to equilibrate the analytical column