Pressure problems
Nico Vonk, Avans+, Breda, The NetherlandsLevelBasic
Symptoms
- Low back pressure
- High back pressure
- Varying back pressure
Low back pressure.
| Possible causes | Solutions | |
| Leakage | Reconnect tubing or replace connecting fittings. | |
| Air bubbles in pump head. | Look for pressure fluctuations. Purge the system. | |
| Worn out pump seal. | Replace the seal. | |
| Check valves not working properly | Take out the check valves and clean ultrasonically, or replace the check valves. |
High back pressure.
| Possible cause | Solution | |
| Particulate accumulation on column inlet frit. | Sample: filter or centrifuge samples | |
| Eluent: filter eluent, clean and top off eluent reservoirs | ||
| System: flush all lines and pump, install in-line system filter | ||
| Accumulation of proteins from biological sample extracts. | Microbial growth in samples or mobile phase (buffers) | |
| Microbial growth in eluent (use 0.1 w-% sodium azide in the eluent) | ||
| Eluent too aggressive (ph too low or too high). | Check column pH stability range. | |
| Precipitation of salts from the sample. | Dissolve the sample in mobile phase beforehand. | |
| Precipitation from buffers (phosphate) in mobile phase modifier(s), such as acetonitrile. | Don't use high percentage acetonitrile (> 50%) mixed with phosphate buffers). Careful with gradients! | |
| High eluent viscosity | For instance when using a methanol/water mixture 50 : 50 v/v it might be better to switch over the acetonitrile/water). |
Varying back pressure.
| Possible causes | Solutions | |
| Air bubbles in pump head. | Look for pressure fluctuations. Purge the system. | |
| Degasser not functioning well | Check the proper working of the degasser in the hplc instrument. | |
| Worn out pump seal. | Replace the seal. | |
| Check valves not working | Clean or replace. |
