Chromatography Forum

Hi all. I am running an Agilent 7200A model GC-QTOF with a DB-23 column installed. Getting bad tune results, and when I run samples or blanks, there is a massive column bleed signal at m/z 216,313,366 (the worst but not only). The DB-23 has been conditioned. Its operating range is 40-250, and my program is ramped 40-230 C. The QTOF had preventative maintenance, including source cleaning, last week. The tune could be an unrelated issue.

Any thoughts? Can post screenshots. Let me know what you want to see. Thanks!

Is the end of the column too far into the source? That can cause bleed and tune problems. Also if the AUX temperature that controls the interface temperature is too high it can cause bleed from the last bit of column before the source.

Thanks for your reply! The interface temp is 245, which should be ok. It might be that the column is installed too far in. I got a good tune on Friday.

I broadened the scan range and see not only 366 but 419, 493, 546, 599. Mostly steps of 53 mz.