| USP Criteria | Specification | Doxycycline | Metacycline | 6-epidoxycycline | 4-epidoxycycline | ||||||||
| Day 1 | Day 2 | Day3 | Day 1 | Day 2 | Day 3 | Day 1 | Day 2 | Day 3 | Day 1 | Day 2 | Day 3 | ||
| Retention time | RSD < 2.0% | 0.1 | 0.2 | 0.1 | 0.1 | 0.2 | 0.1 | 0.1 | 0.1 | 0.1 | 0.5 | 0.1 | 0.1 |
| Capacity factor | >1.0 | 5.9 | 5.9 | 6.1 | 3.2 | 3.2 | 3.3 | 4.1 | 4.1 | 4.3 | 2.4 | 2.3 | 2.4 |
| Symmetry | >0.5 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.1 | 1.0 | 1.0 | 1.0 | 1.0 |
| Area | RSD < 2.0% | 0.7 | 0.9 | 0.4 | 1.4 | 0.3 | 0.2 | 1.3 | 0.1 | 0.2 | 0.9 | 1.9 | 1.1 |
| Theoretical plates/meter | >2000 | 3969 | 3730 | 3533 | 12,160 | 10,438 | 9887 | 14,842 | 12,910 | 11,904 | 5201 | 4549 | 4352 |
| USP Tailing | <2.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.1 | 1.0 | 1.1 | 1.0 | 1.0 |
| Resolution | >2.0 | 2.9 | 2.8 | 2.8 | 2.5 | 2.4 | 2.4 | 2.9 | 2.7 | 2.6 | 3.3 | 2.9 | 2.8 |