Table 2003.13D.
Chromatographic conditions
| Column | Phenomenex Synergi PolarRP, 4.6 × 150 mm, 4 μm particle size |
|
| Mobile phase | Methanol—100mM KH2PO4 (3 + 97) | |
| Flow rate | 1.5 mL/min | |
| Injection volume | 20 μL | |
| Detection | ∼0.10 AUFS at 210 nm | |
| Injection needle wash solvent | Water | |
| Column temperature | 25°C | |
| Run time | 20 mina | |
| Retention times | ||
| Marker compound | Retention time, min |
Relative retentionb |
| Norephedrine | 4.9 | 0.61 |
| Norpseudoephedrine | 5.4 | 0.68 |
| Ephedrine | 8.0 | 1.0 |
| Pseudoephedrine | 9.4 | 1.2 |
| Methylephedrine | 12.8 | 1.6 |
| Methylpseudoephedrine | 13.2 | 1.7 |
a
High protein drink mixes may require a run time of 30 min due to late eluting peaks. Products that contain caffeine require a 10 min column flush with acetonitrile-water-H3PO4 (50 + 50 + 0.1) after at least every 4th injection. Re-equilibrate the column with mobile phase for 10 min after each flush.
b
Relative retention time is calculated as the retention time of the ephedrine alkaloid of interest divided by the retention time of ephedrine, and can be used to aid in peak identification.