What are the maximum changes allowed in a USP method- FAQ
This is a question that is always asked and the following are only guidelines. For exact details, consult the FDA, your regulatory department or the USP.
| Change of Detector Wavelength | Not Allowed (you can vary up to 3nm in accuracy but you cannot adjust the detector.) |
| Column ID | +/- 50% |
| Column Length | +/- 70% |
| Column Temperature | +/- 20% |
| Concentration of buffer salts | +/- 10% |
| Flow Rate | +/- 50% |
| Particle Size | - 50% |
| pH of Mobile Phase | +/-0.2 units |
| Ratio of Mobile Phase Solvents | +/-10% absolute (This adjustment is not suggested) |