Hi  Waqar Azeem Jadoon

heat the column for 300* C for about 20 min, cool down to 150*C, tight the MS nut again, tune @ 150*C itself manually, then share your views again

Selvan

Dear Waquer Azeem Jadoon,

I think your system is OK because m/z 28 is not so high.

Normally, we call the relative abudance of N2(m/z 28) is hogher than 15% of the abundance of 69 when PFTBA was used as a tunning solution.

Please turn one the PFTBA valve and type mass 1: 69, mass 2 28, mass 3: 32 and compare the results. i think relative abundance of 28 will be lower than 15% of 69.

Thanks everybody for your valuable suggestions. Young-Min Kim thank you, I did as you suggested and it solved my problem.

Air leak may cause due to the unfit of the O-ring at the MS interface. Please check that also