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Contamination on GC-FID

GCarmen

Hi Everyone

I work with an Agilent GC6890N and since the beginning of the week, we have a contamination (one peak) in our system which I have no idea where it comes from. I have a picture:

This is a blank run with solvent MTBE (2-Methoxy-2-methylpropan). On RT 1.25 you can clearly see the contamination. 

First i did, was an instrument blank run (split injection), which was clean.So i assumed it comes from the injection or outside my system.

Here is what i tried:

- Fresh/other solvent

- Syringe cleaned/replaced

- Septa and liner replaced

- Wash vials, ans septas cleaned/replaced

- cleaned the inlet

I even did an run with empty vial and the peak is still present, so no solvent issue.

Has anyone another idea, from where this peak can come from?

Thanks in advance and have a nice day! 

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  • 0

    Hi GCarmen,

    Are you using headspace or liquid injection?

    - Headspace: To prevent air contamination you need to blow N2/He into the vial and then close the cap before injecting the sample

    - Liquid inject: 

    + Blank sample inject 1: same headspace method.

    + Blank sample inject 2: single run without inject, vial is zero or blank. Press start on key board GC

    + Replace a new one liner, Column conditioning, cut 10cm of column (inj. port), change another column.

    Chuong

Reply
  • 0

    Hi GCarmen,

    Are you using headspace or liquid injection?

    - Headspace: To prevent air contamination you need to blow N2/He into the vial and then close the cap before injecting the sample

    - Liquid inject: 

    + Blank sample inject 1: same headspace method.

    + Blank sample inject 2: single run without inject, vial is zero or blank. Press start on key board GC

    + Replace a new one liner, Column conditioning, cut 10cm of column (inj. port), change another column.

    Chuong

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