I have a Varian 3800 GC setup for greenhouse gas analyses, N2O through Hayesep N then D to ECD, and CO2 through Hayesep N & Porapak QS to TCD. It works well for these analyses. I've been asked to use this GC for SF6 analyses. My sales rep assured me that SF6 on the ECD would be no trouble. So, I ran some SF6 to test things out and got a huge peak on both the TCD and ECD. Now I can't get rid of the SF6 from the ECD line, TCD line is fine. My salesrep assumed that I had the Porapak QS on the ECD line - she sent me a SF6 chromatogram for this column. To complicate matters, the gradstudent doing the SF6 experiment has no experience with this experiment. He gave me pure SF6 as a standard! My question is: what is the difference between the Hayesep D and the Porapak QS. Could I just disable the TCD line and switch columns? In advance, thank you for your help!