PTFE frit in Quat Pump always dirty

Hello! I have slightly increased the amount of use my HPLC gets but I am having to change the PTFE frit in the Quat pump what seems like a lot more often. Probably once to twice a month. Is there anything else that anyone thinks that could be causing it to get dirty? Or is it more likely to just be from just the increased usage? We do not have a normal maintenance routine as we are a very small company. I am working on developing one.  Thank you for any help you can provide!


ETA: I am having pressure issues when this happens and causes it to stop working. I forgot to mention this.

  • Usually discoloration of the PTFE frit is nothing to worry about. As long as the pressure with open purge valve is below 5-10 bar, while pumping, there is no reason to replace it. That's its function - to filter out any dirt and particles from the solvents. Of course, proper housekeeping should be in place (statements below are for 1290 system, but can also be applied to any HPLC):


    - always use brown bottles, especially for ACN, but also for water and other solvents
    - use membrane filtration to filter solvents before usage; also true for water
    - don´t refill bottles. Rinse with a little fresh solvent first, then stay with volumes which are gone within two days
    - don´t put solvent bottles in the dishwasher, rinse with some fresh solvent, then discard the liquid
    - always go for gradient grade quality at least (even higher, if an MS is connected)
    - there are good and not so good brands on the market. We cannot recommend anything, but Agilent solvents are known good quality

    - do not use technical grade solvents on your LC
    - make sure the glass filter frits are on. Replace them on a regular basis. Do not clean/boil/sonicate them
    - no water, buffer or ACN to be left in the system, if not in use for more than two days
    - We also recommend flushing the entire LC with IPA on a regular basis. Before using the instrument again, flush thoroughly with fresh water. Make sure the instrument gets a PM on an annual basis

  • Sschombu, do you have a procedure to flush with IPA or fresh water?  Our labs concern is not running samples over the weekend and we have ACN as a mobile phase.  You also mentioned something about membrane filtration for solvents.  What is that exactly?


  • There is no procedure as such for flushing with water or IPA. Just go for high quality solvents, flush with water first (if your LC is in ACN, there is no need to flush for a long time. Once the degasser is purged, 3-5 mins are  plenty), then finish with IPA.

    Membrane filtration helps removing small particles from the solvent, which would cause issues on the system. Basically it's a vacuum bottle with a funnel and a strainer. You might want to check here: HPLC Solvent Filtration Assembly and Membrane Filters | Agilent

    There are various materials and pore sizes available.

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