High backpressure or increasing backpressure

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Probable cause		Suggested actions
1	Plugged filter frit	Inspect filter frits in the pumps to ensure they are not clogged, replace if necessary. Inspect inline filter frits to ensure they are not clogged, replace if necessary. Inspect guard column frit to ensure it is not clogged, replace if necessary.
2	NOTE: Using a guard column and an inline filter protects the separation column from premature failure. NOTE: Using a suitable inline filter (e.g. 0.2 or 0.5 µm) and always filtering samples and eluents prevent particulate material from entering your HPLC system.	Flush and, if necessary and allowed by the supplier, backflush the column. Replace the column if necessary.
3	NOTE: Using a suitable inline filter (e.g. 0.2 or 0.5 µm) and always filtering samples and eluents prevent particulate material from entering your HPLC system.	Systematically loosen the fittings of the system working upstream from the waste to the pump and observe the pressure changes. Use the pressure changes while loosening the fittings to determine which tube is clogged. Replace tubing if necessary.
4	Column diameter/particle size too small	(https://www.agilent.com/en/product/liquid-chromatography/hplc-advisor) Ensure that mobile phase viscosity is suitable for the column particle size. Reduce the column length or increase the particle size.
5	Mobile phase viscosity too high	Use a lower viscosity solvent or reduce the flow rate. Use a higher column temperature. Reduce the column length or increase the particle size.
6	NOTE: The eluents should be miscible and should not form salt precipitates over the range of the entire gradient. The eluents should also be properly degassed. NOTE: Store the system properly by flushing out any buffer solutions with water and then storing the system in 50 % isopropanol in water.	Ensure mobile phase compatibility with buffer. Flush the system with water to re-dissolve any salt crystals formed in the system.
7	Column misuse	Determine if the mobile phases are compatible with the column manufacturer's solvent compatibility information. When changing mobile phases, ensure solvent miscibility.

21-Jun-2025