A question about peak defects in HPLC-MS/MS chromatogram

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

9 posts Page 1 of 1
Dear all,

Has anyone encountered the problem shown in the picture. This is a HPLC-MS/MS chromatogram (positive mode). Frequently the signal disappeared, making the peak have many straight lines from top to bottom inside. The mobile phase is A: H2O with 10mM AF and 0.005% FA; B: MeOH with 10 mM AF and 0.005% FA. Same problems happened when using another column (different method and different stationary phase). And I tried the 3rd column to separate my colleague's target analyte in negative mode, it turned out to be OK.
[img]/Users/kennywurb/Downloads/enan_stl.png[/img]
Actually at the very beginning I thought it was the problem of the pump since I found that the exhaust fan was broken and the pump was just too hot. So after I opened the door to release the heat of the pump, the problem was solved. Then after some time, the problem happened again and did not work even I opened the door to let the heat out.

Thanks so much for all your attention.
Kind regards,
Kenny
Can't see the picture. For the tag to work, it has to be an accessible URL.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
tom jupille wrote:
Can't see the picture. For the tag to work, it has to be an accessible URL.


Yes, you're right. Please try whether the following works or not. Thanks for your attention.
Image

Best regards,
Kenny
Hi Kenny,

That doesn't work either. Please follow the guidelines in the sticky post.

Note that you can check yourself if it works or not by clicking the preview button
Thanks for that.
Finally, here is the chromatogram. :P
Image

Kenny
My first thought is that you are seeing air bubbles. Make sure you are adequately degassing your mobile phase. If the problem persists, you might try replacing the transfer line from the column to the MS inlet with narrower-bore tubing in order to add a bit of post-column back pressure and keep the air in solution.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
tom jupille wrote:
My first thought is that you are seeing air bubbles. Make sure you are adequately degassing your mobile phase. If the problem persists, you might try replacing the transfer line from the column to the MS inlet with narrower-bore tubing in order to add a bit of post-column back pressure and keep the air in solution.

Thanks for the reply. I will try that. But how to explain that my colleagues used their columns with the same transfer line and they did not encountered the problem? Would that be a problem related to the turbo spray source? (We are using AB Sciex 3200 Q TRAP)
Actually at the very beginning we thought it was the problem of the pump because the exhaust fan of the pump did not work and the heat could not released. Then we opened the door and keep the pump cool, and the problem solved. But after a period of time, the problem came again.

Also another problem I have observed recently is that after I start equilibration for a few minutes, the icon of mass turned red from yellow, and said that the source temperature was not at set point and I had to press the equilibrate button again and then it works. That's the case.
Would these two problems actually be related?

Thanks for your kind attention and help.

Kenny
another thought: could also be a spray-stability issue. Make sure your ESI spray needle is looking like it should (inner capillary correctly placed, and its end not damaged).
kennywurb wrote:
tom jupille wrote:
My first thought is that you are seeing air bubbles. Make sure you are adequately degassing your mobile phase. If the problem persists, you might try replacing the transfer line from the column to the MS inlet with narrower-bore tubing in order to add a bit of post-column back pressure and keep the air in solution.

Thanks for the reply. I will try that. But how to explain that my colleagues used their columns with the same transfer line and they did not encountered the problem? Would that be a problem related to the turbo spray source? (We are using AB Sciex 3200 Q TRAP)
Actually at the very beginning we thought it was the problem of the pump because the exhaust fan of the pump did not work and the heat could not released. Then we opened the door and keep the pump cool, and the problem solved. But after a period of time, the problem came again.

Also another problem I have observed recently is that after I start equilibration for a few minutes, the icon of mass turned red from yellow, and said that the source temperature was not at set point and I had to press the equilibrate button again and then it works. That's the case.
Would these two problems actually be related?

Thanks for your kind attention and help.

Kenny


To find the real error you have to look in the Windows Event Viewer. Analyst software (if that is what you are using) likes to hide the details of the errors in the Event log for the software.

If there is a problem with the turbo heaters it could be giving problems with fluctuating temperature. Also there could be a difference in the flow rate between your test and the other peoples test which would affect backpressure on the transfer line so that one would give bubbles and the other would not, also differences in mobile phase mixtures could do the same thing. Remove the ESI probe and make sure the inner capillary is only extending past the tip about 0.5mm, if it is farther out than that, or recessed inside the tip it can cause problems. Also make sure the Curtain Gas is set at 15-20, this will help keep any stray droplets from entering the MS.
The past is there to guide us into the future, not to dwell in.
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