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Chapter 02 LC Pressure Issue

January 12, 2022
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Figure :

System pressure is affected by a number of variables including:

  1. the viscosity of the solvent used,
  2. column variables,
  3. flow rate and temperature.

It is important to have a reference point when comparing high or low pressures to the norm. This reference point should be the pressure generated in the system when everything is functioning correctly. It is a good idea to note the system pressure under normal operating conditions each day or each time your HPLC is used. This will allow you to spot any pressure trends that otherwise might go unnoticed.

Pressure problems fall into one of three categories: high, low or fluctuating pressure. They can occur suddenly or be a gradual process. Sudden pressure rises tend to be due to particles from the sample, blocked or damaged tubing or column packed bed collapse. Gradual pressure rises can also be due to particles in the sample, but they can also arise from particles generated in the instrument, for example, debris from vial septa or degrading seals.

Before releasing any high pressure build-up in a system, be aware that the solvent may form an aerosol or spray when loosening connections. Eye protection should be worn and ideally the connection to be loosened should be positioned above an adsorbent material to soak up all released solvents.

The simplest way to troubleshoot pressure problems is using a systematic approach, as highlighted in the following tables for high, low and fluctuating pressure.

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