5973 Tune not passed

[thohry]

Hi all,

The 5973 could pass low mass tune, but failed atune. We have cleaned the source but it does'nt work.
What can be the culprit in this case?
Thanks for reading and any input is appreciated

Rrds

[Consumer Products Guy]

Did you re-set the parameters to the default parameters then try standard autotune?

[jh1]

Did you re-set the parameters to the default parameters then try standard autotune?

If that doesn't work also try ramping the lenses and see if anything looks off, especially the repeller. You can have a repeller that's dirty or slightly out of alignment which would allow a low mass tune to pass but fail an autotune.

[gpronger]

Adding to the thought regarding ramping the lens; a handy practice is to, when the system is operating properly, hardcopy the parameter ramps of the lens and keep them on file. A copy of the parameter ramp when the system is operating properly can be a pretty good diagnostic tool when the instrument misbehaves.

Greg

[thohry]

Thanks all for replies. I cleaned the source and it passed the atotune again.

[AICMM]

thohry,

If I were in your shoes, I would go out and buy a brand new repeller at a minimum. This has a significant impact on high mass ions. I would also, if I had the money, buy a new ion focus since the pin sometimes gets loose....

Best regards.

[thohry]

thohry,

If I were in your shoes, I would go out and buy a brand new repeller at a minimum. This has a significant impact on high mass ions. I would also, if I had the money, buy a new ion focus since the pin sometimes gets loose....

Best regards.

Hi AICMM.
You mean the repeller could be out of shape after some times of cleaning? Or what else can be the reasons for changing it?

Thank you and Regards

[Ron]

I have seen a lot of mass specs where the source had been cleaned, but wasn't really clean. I never use the sheets of abrasive that come with a mass spec, they tend to leave scratches, and in many cases don't seem to remove all the contamination. I always use either aluminum oxide powder/methanol slurry or a high quality non-abrasive chrome wheel polish and a wooden cotton tipped swab for cleaning the metal parts, followed by sonication. If I have one available I break off most of the wooden handle and inserrt the stub into the chuck of a Dremel tool, and polish at low speed. I try to get a mirror finish on all pieces, and sonicate in water, acetone, and methanol. If you use wheel cleaner it stays on the swab better, but you also need to sonicate in hexane as these contain wax.

Don't stop cleaning as soon as the visible contamination is removed, keep on polishing until the steel is very shiny. There may still be a light coat of contamination after the visible is gone. I went in one time when co-workers had spent 20 minutes cleaning off visible contamination without improving performance, and vented and spent an additional hour (didn't have my Dremel tool that day) cleaning parts that looked clean. Performance was back to normal after that.

[pacerlaser]

Does anyone have a set of ramping plots from a properly functioning and clean MS for reference?
Appreciate it.

[MSCHemist]

I sometimes use the green paper to remove charring by the filaments and holes in the source body.

Otherwise my procedure is
Barkeepers friend the 7 metal parts
sonicate in water
sonicate in MeOH
sonicate in acetone
sonicate in hexanes
reassemble and pump down
Do the bake.mac for 8 hours that turns the source and quad to maximum temperature.

[James_Ball]

I have found that mixing the Alumina powder with Citranox to make a fairly thick slurry works better than using methanol. It helps the abrasive stick to the metal parts as you are cleaning them with the cotton swabs. It can also be used with the swabs in the Dremel tool also.

I had times when I was running a 5971 that when the more gentle cleaning did not do the trick I had a pack of the "Shark Skin" polishing cloths, I believe you can get them from SIS ( Scientific Instrument Service) ranging from about a 1500 up to a 18,000 grit. Start with the roughest 1500 and really grind the surface especially on the repeller, then work through the cloths in sequence and when finished the surfaces will be mirror polished. This always brought the sources back into shape, but doesn't seem to be needed as much since the Inert sources came out.

Even the green sanding paper will clean a source, but the more polished it is, the longer it will go between needing to be cleaned and the easier it will be to remove the contaminates.

Also keep an eye on the Repeller insulators, if they begin to have dark marks on them, you may want to replace them as the metal that slowly imbeds in them can begin to conduct. Same for the brown lens insulators but not nearly as often.

[chloesabrina]

We use barkeepers friend mixed up to a thin slurry. I use q-tips and sometimes will use the green abrasive paper to lightly smooth the repeller. I have had an issue like that right after a source was cleaned and had to re-clean and sonicate. Normally it's when there is still something adhering to the source parts (especially in all the "holes")