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

  • Hi there!


    I will definitely make sure to implement your suggestions. I am having pressure issues and replacing it does help but could there be more to it than that? I am new to HPLC and this community has helped significantly.


    Thank you very much!

  • Good solvent quality is vital, so try a different supplier or a better grade. As I said earlier, membran filtration of all solvents is a good idea. Make sure a PM gets done, if the system hasn´t seen one in the last twelve months.

  • The previous replies are all spot on. While quality and cleanliness are critical to good chromatography, a dirty frit might indicate it's time for new piston seals.   Check you maintenance log, or if you don't keep records download the Lab Advisor utility from the Agilent firmware site.  Lab Advisor includes many features, diagnostics, EMF counters, and firmware updating.


    You can also try vacuum filtering your mobile phase through 0.2 micron filters, if you suspect things are growing in your mobile phase (e.g. algae or bacteria)


    Directions to LabAdvisor (and Firmware)


    Please visit for downloading the latest Agilent LC firmware and Lab Advisor.


    Once there, click on Firmware Update Tools & Procedures, select Firmware_Set_UpdateTools/LabAdvisor/M8550-60118 Agilent Lab Advisor Disk and then Download.

  • So we had this problem when we first starting using the 1260 systems. We would add a standard column (100 x 3.0mm), and after less than 100 injections of solvent based material it would give us huge backpressures and stop the injections. We blamed the column manufacturer at first, so switched to another column from Agilent, and it still happened. We changed various tubing, heat exchangers, and frits for the solvent lines, all with only short-term success. 


    We eventually traced it back to needing to filter our mobile phase solutions. We now filter absolutely everything attached to a HPLC line using 0.2um nylon filters. We also added a pre-column filter (0.2 or 0.5um) and a guard column and now we have no pressure issues. We change the filters when we see poor peak shape, or increasing pressures (we follow the pressure profile for each batch). We also try to flush out the HPLC system every 6 months, there's a HPLC flushing solvent available from Agilent which we use, and I can send you on the protocol we use if you want.


    So, filter everything, and clean your HPLC before you try doing more injections, otherwise we only got temporary relief of the pressure buildup. Our systems were brand new when we experienced these issues. 


    Hope this helps!



  • When I got here (very small QC lab) they had the mindset of "we use it so little that we will just figure out problems as they arise." We have since started going through a lot more samples so I created a maintenance log and am going to try to do routine maintenance on it. Right now we filter through glass filters but who knows when the last time they were changed. I also replaced the piston seals. I've tried to utilize Lab Advisor but it isn't working correctly on my computer and my tech person isn't being of much help with it. I might try reaching out to a representative and see if they can help me. I do think flushing out the system and doing the list of suggestions above will help. Thank you all, I would be lost without you!

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