5975C GC/MS 219 ION HIGH

Are you using the BFB Autotune or the BFB Tune?  Sometimes one works better than the other.

You can also try switching filaments or replacing the filaments and repeller insulators (G1099-20133) and the lens insulator (G3170-20530).

We normally use BFB Autotune. BFB Target Tune also fails with the default settings. The filaments are both new and both act the same. When I cleaned the source I found the lens insulator was cracked so that was replaced. Dynamically ramping the entrance lens voltage and manually setting it to a lower than normal value at ion 219 brings it down. BFB Target tune also ramps the entrance lens and you can manually modify the voltages that result. We've never had to do this before so it seems there is something wrong?

We normally use BFB Autotune. BFB Target Tune also fails with the default settings. The filaments are both new and both act the same. When I cleaned the source I found the lens insulator was cracked so that was replaced. Dynamically ramping the entrance lens voltage and manually setting it to a lower than normal value at ion 219 brings it down. BFB Target tune also ramps the entrance lens and you can manually modify the voltages that result. We've never had to do this before so it seems there is something wrong?

Sometimes having the 219 higher than 69 happened a lot on the 5973, haven't really seen it much on the 5975/5977 due to different detector back end.  You could try re-cleaning and verifying everything, maybe also squeeze the lens assembly and the source body together when putting back together and tightening the gold screw since the source body is the only electrical connection to the drawout plate and cylinder.  You can use the link below to a cleaning document that has a lot of useful details.

How to clean an Agilent GCMS HES Ion Source

Hi elisteve,

I was following your progress , glad it worked out with Ryan's help. One point of information that is important here is that the BFB tunes are built off of the Atune. If there are tuning issues, a quick check is to Atune, then followed by one of the BFB tunes to make sure all are fresh and up to date.

I took it down and cleaned the source again (for the 3rd time). I didn't see anything amiss, but now the 69/219 ratio is normal and bfb tune passes. Not sure what the issue was but it appears to be fixed.

We still have the issue of 219 ion being the base peak instead of 69 on our 5975C used for EPA volatiles analysis. This occurs during atune and also the BFBAutotune. The only way we can get it to pass a BFB tune is to ramp the Entrance Lens Offset to lower 219 into the range it needs to be. Otherwise the 173 to 177 ions in BFB are too high. We are using the BFBAutotune routine modified to ramp the offset. Even though it generally passes, we would like to correct this issue. Any ideas?