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Pressure increase in HPLC

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Over time a gradual pressure increase in HPLC is noticed.


Increase in pressure points at an obstruction in the HPLC flow path. This obstruction can be at the column, tubing, connections, inline filters, or any other part in the flow path.


To find the obstructed part in the flow path, disconnect the components one by one and check if the pressure goes back to normal. Start with the last part in the flow path, and work your way to the front end of the flow path until the source is found. Usually it is either the column, the pre-column, the column-filter or one of the tubes between injector and flow cell. Other less likely sources are hte injecotr and waste line.

IMPORTANT: Make sure to disconnect any connection only after the system pressure has come down (close) to zero. Then switch back on the flow. If the pressure is still significant, stop the flow, wait for the pressure to drop and disconnect the next part etc until the blocked part is found.


Replace the part that causes the obstruction. If a column shows a pressure increase in a short period of use (small number of injections), there is usually an underlying problem. In such case clogging of the column is most likely happening due to:

  1. mobile phase
  2. sample
  3. sample buffer
  4. additive (i.e. derivatization reagent, microdialysis liquid,…)

Especially new UHPLC columns are easily clogged when particles are introduced in the flow path. Pay attention to in-line filtering points, chemical compatilibilty among solutions and the sample preparation.

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