Overview

Mobile phase inlet filters play an important role in protecting HPLC systems from particulate contamination originating in solvent reservoirs. Before a new polyethylene inlet filter is placed into service, it is recommended that the filter be properly wetted and primed.

Priming helps ensure that solvent can move freely through the porous filter material and can improve pump performance during system startup.

Why Priming Is Important

Polyethylene inlet filters contain a porous structure that can trap air during manufacturing, storage, or installation.

If trapped air remains within the filter, it may contribute to:

• Slower system priming
• Inconsistent solvent uptake
• Pump cavitation
• Flow interruptions
• Extended startup times

Proper wetting of the filter allows solvent to fully penetrate the porous matrix and displace trapped air.

Recommended Solvent Selection

For best results, use the same solvent system that will be used during the chromatography method.

Examples include:

• Water
• Acetonitrile
• Methanol
• Buffer solutions
• Mobile phase mixtures

Using the intended mobile phase helps avoid introducing unnecessary solvent compatibility variables during startup.

Priming Procedure

Step 1  Place the inlet filter into a clean container containing sufficient solvent to completely submerge the filter element.

Step 2  Position the container in an ambient-temperature ultrasonic bath.

Step 3  Sonicate for approximately five minutes.

The ultrasonic energy helps remove trapped air and promotes rapid solvent penetration throughout the porous material.

Step 4  After sonication, install the filter into the solvent reservoir and proceed with normal system priming procedures.

If an Ultrasonic Bath Is Not Available

An ultrasonic bath is helpful but not required.

When sonication equipment is unavailable:

• Fully submerge the filter in the desired solvent.
• Allow the filter to soak until the solvent naturally wets the porous structure.
• Use a longer soaking period to ensure complete wetting.

This approach can be equally effective, although it may take longer.

Extended Soaking Considerations

Extended soaking does not normally damage polyethylene inlet filters.

If the filter remains submerged longer than necessary:

• Performance is not adversely affected.
• The filter material is not harmed by routine wetting.
• Additional soaking time simply allows further solvent penetration.

As a result, exact soaking times are generally not critical once complete wetting has occurred.

Best Practices

To support reliable operation:

• Prime new filters before installation.
• Use the intended mobile phase whenever possible.
• Ensure complete submersion during wetting.
• Remove trapped air before connecting the solvent line.
• Inspect filters periodically for contamination or blockage.

These practices can improve solvent delivery and help maintain consistent HPLC performance.

Key Takeaways

• Polyethylene inlet filters should be wetted before use.
• Priming helps remove trapped air from the porous filter structure.
• Using the same solvents as the analytical method is recommended.
• Five minutes of sonication is generally sufficient.
• Extended soaking will not damage the filter.
• Proper priming supports reliable solvent delivery and pump performance.

For Mobile Phase Inlet Filter Specifications, Filter Options, Product Images, and Ordering Information, view Mobile Phase Inlet Filter Specifications, Filter Options, Product Images, and Ordering Information.