pre-column filters

<p><span>I have inherited a filter on one of our 50X2.1mm columns.</span></p><p></p><p><span>1) Why and when is a filter useful?</span></p><p></p><p><span>2) How do I test whether the filter is fulfilling my expectations? Are there additional tests to ensure the filter has not begun doing additional tasks?</span></p><p></p><p><span>Thanks,</span></p><p><span>Jackemeyer</span></p><p><span>Tempe, AZ</span></p><p></p><p><span>PS I searched "filter" and read the relevant discussions. If this question has been answered, please feel free to simply redirect me and others to the approriate link.</span></p><p><span>PPS When I "start a discussion", two options are available -- what is "</span><span>start a new project"? What are projects and where can I find them? Are they searchable? Are they public or private?</span></p>


  • dougm

    The ACQUITY UPLC In-Line filter is a replaceable 2.1 mm ID UPLC column frit located inside a low volume holder. It is designed to catch microparticulates that may plug/foul a UPLC column. They come standard with every UPLC system. It plays the same role as in-line filters in HPLC systems.

    Unfortunately, there is no 'test' that I am aware of that can assess/measure/determine if this filter is fulfilling your expectations. One way to determine if it is doing 'anything' is if you occasionally have to replace the filter/frit because your system is experiencing pressure increases. In this case, it is plugging instead of your UPLC column and is working as designed.

    If you never experience pressure issues then perhaps the in-line filter is not necessary. Or, you experience pressure increases AND efficiency loss(es) due to chemical (not particulate) fouling of the frit and stationary phase. In this case, perhaps a VanGuard pre-column would be more useful. VanGuard pre-columns are 2.1 mm ID x 5 mm length guard columns packed with the same 1.7 um and 1.8 um stationary phases as our UPLC columns. These would be used instead of the in-line filter.

    I hope this answers your question. If you have additional questions, please post them. I am also hoping that some UPLC system users will comment on the utility/usefulness of the in-line filters and/or VanGuard pre-column.

    Good luck,


  • lizh

    Thank you Doug for your answer and this gives me the opportunity to add a comment or rather two.

    Many customers use the filters routinely to no adverse effect.

    I do advocate bandspreading tests on systems. If done routinely you would know if the system efficiency has been affected by a bad fitting and here, the effect of the additional filter.

    It really does not matter which bandspead method, but just use the same consistently. This is a really great troubleshooting tool.

    Best regards,


  • Elizabeth Hodgdon wrote:

    > It really does not matter which bandspead method, but just use the

    > same consistently. This is a really great troubleshooting tool.

    Do you have a specific method in mind for a (100mm X 2.1 column)?

    Or is this simpler than I am assuming...


  • The simplest thing to do is to measure the isocratic efficiency of your peak of interest both with and without the in-line filter. Is its effect acceptable to you? Only you can answer that question. Early eluting peaks will be affected more than later eluting peaks.

    If you wish to measure band spread, here's how it was done in the attached paper:

    All band spreading measurements were made by injecting a 0.01 mg/mL solution of thiourea in 65/35 ACN/H2O. Flow rates used were 0.05, 0.1, 0.15, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mL/min. Peak width was measured at 13.4% peak height (4?). Mulitply peak width (min) by flow rate (mL/min) and you get your band spreading in mL.

    The attached provides complete details on detector settings, detection wavelength, etc.

    To measure system band spreading, take the UPLC column out of line, replace with a low volume ACQUITY union, and then inject the thiourea solution under isocratic conditions.

  • This should keep me busy for a while, thank you :)

    Much appreciated,

    D Jackemeyer

    Tempe, AZ