Carry over in my blanks after maintenance

I'm seeing carry over contamination in my blanks after running SSTs.

The more blanks I run the bigger the peaks seem to get? I'm not sure what is going on. They're fresh blanks and this has only started after doing some general maintenance. 
Including: - Source clean, quad clean, gold seal change, liner change, septum change.

The first image is the blanks before the SST, and the second is the final blank after the SST.

Any advice welcome!

  • Hi

    Change wash and waste vial from autoinjector then check....

  • Hi,

    Thanks for your response. I've done this, also changed the syringe and the gold seal again.  Really not sure where to go next

  • Ok..

    Did you cut little inch column from both side of inlet and detector...

  • No, only because I don't think the issue is in the column. 

    The first blank I run is always fine, and i've also ran air injections and there are no ghost peaks.

  • Generally, when doing general maintenance then it's recommended to trim column from both side..

    I assume ion source cleaning n inlet maintenance is done in proper way already..

    Can you share atuotune report...

    If all ok..then you can bake out MS...

  • This is a TQ system running MRM or MS1/MS2 Scan mode?  Would you please share a spectrum of the peaks?  Are they your normal sample peaks?

    When you cleaned the inlet, did you also replace the split vent trap?  Did you check that the side arm of the SS inlet is clean?  You may need to have the copper split vent line replaced that goes between the inlet body and the split vent trap. It captures a lot of stuff before the split vent trap and it needs to be either rinsed out or replaced every...well, it's sample matrix and number of sample dependent.

    One other easy thing to try.  Set up your GC for 1.5psi inlet, 500ml/min split and slowly hand inject 80 or so uL of your normal sample solvent – without acquiring the data. Then reload your normal run method and turn the oven up to the normal run final oven temperature and let it sit there for some minutes to make sure that any residue is out of there.  This sort of rinses out the inlet using a very high split ratio and very low column flow.

    Quad clean? It's never recommended for an operator to clean the quad as the chances of disaster are high.  Quad cleaning is only about ion peak shapes, like in tune, and ion throughput and not chromatographic peaks.

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