What happens when a column deteriorates?
Q16. What happens when a column deteriorates?
Common symptoms of column deterioration include increased column pressure,
decreased theoretical plates, shortened retention time, poor peak shape,
and decreased resolution.
Please refer to Troubleshooting T1 Poor peak shape.
Q17. How can I confirm the deterioration of the column?
Test the column under the same conditions as the attached inspection report. Use the same instrument every time to record the performance of the column. Record standard values over time and change to a new column if they deviate significantly.
| Valued | Potential Causes of Deviation | |
|---|---|---|
| Capacity Factor (ｋ') | If the stationary phase is stripped, retention time may shorten. | |
| Theoretical Plates (N) | May decrease due to adsorbed impurities or a disrupted packing bed. | |
| Peak Asymmetry (S) | May deviate due to deterioration of packing material or adsorption of impurities. | |
| Pressure | May increase due to clogging of column filter, sample adsorption to packing material, compression of packing material, and other causes. | |
Q18. What should I pay attention to when I use semi-micro columns?
Use an injector, tubing and detector cell designed for semi-micro columns.
Confirm that the mobile phase flow rate is proportional to the column's
cross-sectional area. For more information, please refer to Technical Information
, Scale Up and Scale Down(PDF 878 KB)
Q19. What should I pay attention to when I use UHPLC columns?
- Use a UHPLC instrument if available.
- For conventional HPLC instruments:
- Shorten response of detector (e.g., 0.02 sec).
- Use an injector, tubing and detector cell designed for UHPLC columns.
- Column pressure should be 30 MPa or less (60 MPa or less for COSMOCORE series).
Q20. How much sample can be loaded on a preparative column?
Sample loading capacity may differ depending on the peak resolution and solubility in the mobile phase. Optimize loading capacity using an analytical column, and determine loading capacity on a larger column in proportion to cross-sectional area. For scaling up from an analytical column to preparative separation, please refer to Technical Information, Scale Up and Scale Down (PDF 878 KB)
Q21. What should I pay attention to when I use both reversed phase and normal phase on the same instrument?
When switching between normal and reversed phase, replace the mobile phase
with a solvent in which both mobile phases are miscible, such as ethanol,
then replace with the new mobile phase.
Mobile phases for reversed phase (e.g., methanol, water) and normal phase (e.g., hexane) cannot be mixed.
