I have intermittently have flat topped broad peaks with m/z mostly 73,147,281,(327,341) and sometimes just 341.
I have looked on web and its PDMS - polydimethylsiloxane.
I do use SPME injection very occasionally but this problem occurs with autosampler injections.
I have also noticed broad peaks with MS of most recently injected material appearing in subsequent injections.
I have replaced liner,wool and septa but problem re-occurs. I guess 2nd problem might be contaminated gas carrier line.
Anyone help?!

David