Resource Hub / ChromaBLOGraphy / What can I use to filter my mobile phase

What can I use to filter my mobile phase?

6 Nov 2016

If you are using mobile phase that contains salts or, generally, any components that are weighed out for its preparation, you will need to filter the solution before using with HPLC or UHPLC.

The most common type of filtration is membrane microfiltration.

We sell an extensive group of products for this and they are discussed very well in a blog post written by one of my colleagues entitled “Simplifying your Membrane Microfiltration Glassware purchase”

We sell membrane filters in polypropylene and nylon to go with the above glassware, although it is possible to use membranes made of other materials that you might find in 47 mm diameter size from other vendors.  Nylon is often preferred for aqueous solutions that are fairly neutral or slightly basic. Polypropylene is preferred over nylon if your solution is acidic or when using less polar organic solvents.

The other type of filtration you might consider is our Hub-Cap Filter Kit.


The Hub-Cap Filter Kit can be used with 4 Liter solvent bottles, or with any media bottle that has the same type of threads (which are 38-429).  An example of such a media bottle is the one shown here from Wheaton, the container in the middle:

The 4-Liter solvent bottles are the ones that normally come with solvents when they are purchased for your lab from a supplier. These are usually amber and look like this:


Hub-Cap Filter Kit, catalog 26395, comes with the following:



  1. ¼” OD x 1/8” ID FEP lined Tygon tubing
  2. Tube compression fitting (HDPE)
  3. Hub-Cap bottle adaptor nut (HDPE)
  4. Filter inlet cap (HDPE)
  5. 47 mm polypropylene filter membranes (one of each included): 0.22 µm polypropylene filter membrane, catalog #26397 and 0.45 µm polypropylene filter membrane, catalog #26396.  Please see * for other options.
  6. 47 mm grid (FEP)
  7. Grid support (PTFE)
  8. Bottle adaptor (PTFE)
  9. Vacuum hose barb (HDPE). Fits tubing ID between 5/16” to 3/8”, can be purchased separately as catalog #25925.

*Also available are 47 mm Nylon filter membranes, which are not included in kit, but available for purchase separately:  0.22 µm Nylon filter membrane, catalog #26399 and 0.45 µm Nylon filter membrane, catalog #26398

To use the hub cap filter kit, you would attach a vacuum pump to the barb on the side of the cap and then draw in the unfiltered solution through the tubing on top. The membrane would be replaced after each usage.

Although this kit is designed for use with 4-liter solvent bottles, you can purchase the Opti-cap adapter, catalog #27197, to use this kit with a GL-45 bottle.

I hope you find this post helpful.

Thank you for reading.