After changing the septum of my Focus GC connected to a DSQ II MS and after a complete cleaning operation on it, my mass spectrum became completely random. It shows me only base peaks in a completely random m/z ratio and at some RT it shows nothing. If I inject only acetonitrile, it shows me visible background noise while if I inject only acetone, it shows me a very low (near zero) baseline with a perfect solvent peak.
Could be a column problem? I cannot do any kind of analysis in this situation because i cannot recognize any analyte inside my sample.
Check your autotune result. And then compare the baseline level and their MSs with previous runs (before cleaning). You should able to see minimal amount of column bleeding even you have just installed a new column.
Florian Obersteiner
yes, i autotuned it with no problem.. i have a feeling about a fragmentation problem...
Steven Sai Hang Ho i can't identify column bleeding because my MS spectrum is completely random
Florian Obersteiner
do you mean the distance between the end of the column and the ion source? i already tried to move the column in and out trying to modify the distance but nothing change.. my big worry is about the random base peaksUPDATE: I loosened the nut of the transfer line and moved the column in and out just a little until i felt the the column can't go no longer inside. Staying in this situation, i screwed the nut. I'm waiting for the vacuum and i will do another tune.
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