Chromatography Forum

hello everyone, I am new to this forums and need some help. I run a 5890 connected to a 5972. This particular instrument is giving me some problems at this time I can't pass a BFB tune due to the fact that ion 175 is not present at all in any of the scans, also the baseline is a bit noisy but not to bad.

This is what has resently been done to the instrument, it was taken down and the source was cleaned, both filaments were replaced, the filament cable, power supply, and electron multiplier were also replaced. The top board and side boards were tested and both were found to be doing their respective jobs well. Also the quadrapoles are in good shape. I can get a very good tune of 69 at an abundance of around 1 million, 219 at about 50% of that and 502 at around 2%. With an Em voltage of 1950.

The bfb tunes are fine with all other ions being scanned at around the middle of their tolerances, I have tried manual and purged injections and nothing has worked so far any suggestions are greatly appreciated. TIA

What I'd try first would be to plug the transfer line interface with a blank nut, and see if the issue was better, worse, or the same. this would help isolate whether your issue is mainly MSD or GC.

what's the peak width of ions m/z 69, m/z 219 and m/z 131? When you have problem with m/z 175, most of the times, the peak width is kind of too large. That will affect the resolution of the MS. Adjust amugain and amuoffs to set the peak width to around 0.50.

dytrdr5.

I agree with JI2002 that the peak widths of 131 and 219 especially have to be around 0.5, preferably right at a bit below. I would also suggest you look at your scan rate to make sure you are collecting enough scans across the peak (funny as that sounds) and I would suggest you look at your ion threshold. My experience has also been that you want more 219 area than 131 area. Finally, what is 96 doing, is it fine?

Best regards.

thank you guys lowering the peak width to 0.47 is now allowing for a peak width of 0.5 for all 69,219, and 502 before it was around 0.55 also ion 175 is now being resolved in my tunes and the instrument is up and running. once more thanks for the help.