Chromatography Forum

We have a Waters Xevo TQ-S that was operating normally in both positive and negative modes, except some loss of sensitivity. We thoroughly cleaned the source, cone, block, and Stepwave optics, then pumped down for 48 hours. We can get Intellistart to tune "resolution" and "calibration" files in ESI+ mode, but it repeatedly fails to complete in ESI- mode, complaining about the 1925.6 ion.

I tried to touch up the tuning manually until it looks fairly good visually before launching Intellistart, but it seems to ignore my starting settings.

Any ideas where to troubleshoot?

Possibly we disturbed something during the cleaning, but ESI+ passes OK.

Also,
I noticed Waters appears to create and use one resolution file and one calibration file for both positive and negative modes. Do these files contain both polarity tune parameters? How do I link/associate the resolution and calibration files when I have a method with switching polarities?

I am no expert but we have a calibration file created by intellistart that is used for all methods. Resolution values we set in each tune file manually after new calibration. Intellistart print new values but does not update the tune files. If one use old tune file after new calibration the resolution may be off. I try to keep dates on file name to match tune and calibration date.
To my understanding, these values needs to be manually written in all the tune files after each new calibration.

Possibly you could try higher infusionrate of setupsolution during calibration to boost signal.

Sometimes a worn ESI capillary needle tip causes trouble. Maybe give this a try.

Best regards
Jörg

Waters do positive and negative separately because you need to dilute the solution for one of the two modes. You can copy the resolution settings manually from one of the resulting .ipr files into the other, and save it with an appropriate name. You can attach any calibration file to any tune file using the "Calibration" - "Set Linked Calibration" menu options in the tune-page. Hope this helps a bit! I'm sorry I can't remember the dilution for each polarity.

Solved. We were trying to use the diluted solution for both ESI+ and ESI- modes. The ESI- is much less sensitive and wouldn't pick up the signal reliably without using the undiluted solution. This is not described in the tuning solution package insert or the Waters software.