carry over in UPLC as front end to QPXE

Carry over found in UPLC as front end to QPXECleaned injector POD, Changed loop, changed needle,changed Strong wash,weak wash,mobile phase.Carry over coming after sample injection is more than 0.5% of sample concentration. This carry over not found in other system.

Answers

  • Hello:

    I am afraid there are not quite enough details to really help you, attached is a document that goes through the suggested systematic steps that you might consider. I would need to know the following:

    (1) What happen when you run a well behave method? One that you are always successful with. At Waters we would use the qualification test/installation test

    (2)Can you confirm that this is an existing method you are running on the UPLC?

    (3) What is the method - injection volume, injection mode and washes?

    (4) What happens with blanks, make a standard injection and then follow with multiple blanks, do the peak areas reduce? Next make a series of zero volume injections - what happens? This will determine if it is carryover or contamination.

    (5) What happens when you swap to a different injection mode? Try Full Loop and then the other partial injection mode to the one you were using.

    After this information we can further assist. And we can send better information once these initial questions can be addressed. It could easily be as little as incorrectly seated, or poorly made sample loop that has a reservoir that is creating the carryover, or as ever could be something else though. Please note the order in which we change things will change with the results of the information that you provide.

    Let us know.

    Liz

    Edited by: Elizabeth Hodgdon on Feb 23, 2009

  • Hello:

    I am afraid there are not enough details to really help you, attached is a document that goes through the suggested systematic steps that you might consider. I would need to know the following:

    (1) What happen when you run a well behave method? One that you are always successful with. At Waters we would use the qualification test/installation test

    (2)Can you confirm that this is an existing method you are running on the UPLC?

    (3) What is the method - injection volume, injection mode and washes?

    (4) What happens with blanks, make a standard injection and then follow with multiple blanks, do the peak areas reduce? Next make a series of zero volume injections - what happens? This will determine if it is carryover or contamination.

    (5) What happens when you swap to a different injection mode? Try Full Loop and then the other partial injection mode to the one you were using.

    After this information we can further assist. And we can send better information once these initial questions can be addressed. It could easily be as little as incorrectly seated, or poorly made sample loop that has a reservoir that is creating the carryover, or as ever could be something else though. Please note the order in which we change things will change with the results of the information that you provide.

    Let us know.

    Liz

  • Hello,

    lately I had a carry over problem too.

    Had to call the service, and the waters guy came with a sample manager maintenance kit and replaced anything, what could be replaced with the kit.

    Had you made a Leak test?

    - At the Acquity console, Sample manager, Maintain, make a wash syringe static leak test. (Guess, the test fails. That happened on my system)

    - In the sample manager, behind the trays, there is the wash station. The right of the two "towers" has a seal which could be too loose to be dense. If you have an old sample needle, you can insert this needle into the "tower" to check if the needle has enough resistance when it passes throug the seal. If it goes too smooth, the seal is too loose. By turning the "tower" a little, this seal could be loosen or tighten. If you're not experienced with the maintenance of the sample manager you may call waters service for assistance or for fixing the problem.

  • Hello:

    First, thank you for this data

    Often with carryover, to prevent multiple visits the FSE will swap the known trouble makers, but you are correct the "wash station block" can be source of contamination. Check the injection port and injection port o-ring for buildup of material, and replace if necessary. I am going to check into the statement about it wearing!

    If the needlewash is not working well this can lead to poor washing and hence carryover. Here is more data as sometimes a picture's worth a 1,00 words!

    Liz

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