Blank Run

Hi

I have noticed something different this morning. I did a black run without injection( after I changed the inlet and septum) using my method(same method) continuously for three times. All the three times I am getting different chromatogram, as seen below. Can anyone help me and explain why they are different and is there anything wrong which I need to correct. I am using GC 7820 A with FID Detector.

Run 1

Run 2

Run 3

 

 

 

Thanks in Advance

Revathy

Parents
  • hi

    that is column related issue

    please conditioning the column and detector and check

  • Column : HP-5 30x 0.32x0.25,

    Hi Krishna

    Thanks,  I have conditioned the column on Friday for about 2-4 hrs with the above condition.  I believe both the column conditioning and the Detector conditioning is same.  Correct me if i am wrong.  I am using He as a carrier gas.  If anything needs to be changed in the above conditioning method please advise me.

     

    Regards

     

    Revathy

  • Hi Revathy,

    It seems like the conditioning method is pretty good. However, you do not need to go maximum temperature all the time, generally; 30degC above the analysis method for Inlet/Detector/Column will also work unless you have high boiling compounds. Keeping the column temperature lower than the recommended will help to prolong the life of the column.

     

    So, back to your original question. The 3 blanks shows that the residue compounds in the system are reducing which is good. If you set the Y-scale same as the first Blank, then you can see that the baseline is getting better (or you can try overlaying the 3 Blanks). If you still see the residue compounds even after much conditioning, then; you may want to clean the inlet with some MeOH or replace the Split Vent Trap Cartridge or clean the Split Vent copper tubing. These are some of the possible places where contamination can occur.

     

    Hope these are helpful.

    Regards,
    Kelvin Tan

Reply
  • Hi Revathy,

    It seems like the conditioning method is pretty good. However, you do not need to go maximum temperature all the time, generally; 30degC above the analysis method for Inlet/Detector/Column will also work unless you have high boiling compounds. Keeping the column temperature lower than the recommended will help to prolong the life of the column.

     

    So, back to your original question. The 3 blanks shows that the residue compounds in the system are reducing which is good. If you set the Y-scale same as the first Blank, then you can see that the baseline is getting better (or you can try overlaying the 3 Blanks). If you still see the residue compounds even after much conditioning, then; you may want to clean the inlet with some MeOH or replace the Split Vent Trap Cartridge or clean the Split Vent copper tubing. These are some of the possible places where contamination can occur.

     

    Hope these are helpful.

    Regards,
    Kelvin Tan

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