No clear peaks with Triple Quad - help needed with tuning

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

10 posts Page 1 of 1
Hello,

I (student) just started working with Triple Quad (Quattro Premier) and the software MassLynx. I have to tune perfectly ESI and the Analyser to detect quercetin. Therefore I use just 16 uM quercetin mixed with methanol. Unfortunately I never see stable peaks. It always looks like a crown with lots of small peaks - do you know what I mean? My professor just said "keep on tuning" but this is so frustrating. Nothing works. I see this crown when I use MS and MS2. But as I use collision gas, both peaks are gone. Even though I thought the sense of MS2 was to see peaks with this gas. When I look for fragments with the daughter scan, I can see them. But they aren't stable and well defined. Lots of crowns here aswell.

I hope somebody understands me and can help.
Is the crown the peak pattern of the masses?

If so you are seeing isotopes or interference near the molecular mass. Can you post a screen shot of what you are seeing?

You may want to increase the concentration of the Quercetin, I normally begin tuning with a 1ppm( 1 microgram per milliliter) solution using infusion at about 5ul/min flow rate. If the signal is too strong then it can be diluted, but you get a better signal to noise ratio for easier tuning to the compound.

Tune MS1 to the molecular ion, then introduce collision gas and run MS1 at molecular ion and scan MS2 to get the daughter peaks, then you build a method looking for the combination of MS1/MS2 at optimized gas flow and temperature conditions.
The past is there to guide us into the future, not to dwell in.
In my opinion, it would be best to have someone with experience to show you the ropes on-site. Is there no one in your lab that has developed methods on that instrument?
Rndirk wrote:
In my opinion, it would be best to have someone with experience to show you the ropes on-site. Is there no one in your lab that has developed methods on that instrument?



Hey, unfortunately not. Nobody has time to help me...this is really quite difficult for the beginning.
James_Ball wrote:
Is the crown the peak pattern of the masses?

If so you are seeing isotopes or interference near the molecular mass. Can you post a screen shot of what you are seeing?

You may want to increase the concentration of the Quercetin, I normally begin tuning with a 1ppm( 1 microgram per milliliter) solution using infusion at about 5ul/min flow rate. If the signal is too strong then it can be diluted, but you get a better signal to noise ratio for easier tuning to the compound.

Tune MS1 to the molecular ion, then introduce collision gas and run MS1 at molecular ion and scan MS2 to get the daughter peaks, then you build a method looking for the combination of MS1/MS2 at optimized gas flow and temperature conditions.



Hey,

yes it is the crown of the peak pattern of the masses. Probably my gain was to high? When my gain is lower the crown goes away and my peak looks a little bit better. I understood what MS2 is there for but unfortunately I cannot see anything at all with collision gas in this mode. When I look for fragments with the daughter scan mode it works perfectly well. I am going to try it with a higher concentration. This is so frustrating.. I am very interested but it just won't work out...Thanks for your advice. I will try sending you my document with the screenshots via mail
NoraStern wrote:
James_Ball wrote:
Is the crown the peak pattern of the masses?

If so you are seeing isotopes or interference near the molecular mass. Can you post a screen shot of what you are seeing?

You may want to increase the concentration of the Quercetin, I normally begin tuning with a 1ppm( 1 microgram per milliliter) solution using infusion at about 5ul/min flow rate. If the signal is too strong then it can be diluted, but you get a better signal to noise ratio for easier tuning to the compound.

Tune MS1 to the molecular ion, then introduce collision gas and run MS1 at molecular ion and scan MS2 to get the daughter peaks, then you build a method looking for the combination of MS1/MS2 at optimized gas flow and temperature conditions.




Hey,

yes it is the crown of the peak pattern of the masses. Probably my gain was to high? When my gain is lower the crown goes away and my peak looks a little bit better. I understood what MS2 is there for but unfortunately I cannot see anything at all with collision gas in this mode. When I look for fragments with the daughter scan mode it works perfectly well. I am going to try it with a higher concentration. This is so frustrating.. I am very interested but it just won't work out...Thanks for your advice. I will try sending you my document with the screenshots via mail


I will be away at Pittcon next week but I will try to see what you send and if I can help. If I don't have access to it then I will definitely be able to help more after next week :)

If you turn on collision gas and are only scanning with MS2 you won't see any ions. The daughter scan mode is what you use for MS2 work, so it is working as it should. After you do the daughter scan, you should take the m/z that show up in that scan and build the SRM or MRM from that (depending on what the software calls the full triple quad method). Use the mass you get in MS1 scan which is usually the molecular ion and enter that in MS 1, then the ions you found in the daughter scan will go in MS 2 and you will optimize the response by adjusting the collision gas. The source gas and temperature setting can then be optimized looking at the response from the MRM scans.
The past is there to guide us into the future, not to dwell in.
p.s. I don't really use Google+ but I can be reached at the email there.
The past is there to guide us into the future, not to dwell in.
James_Ball wrote:
p.s. I don't really use Google+ but I can be reached at the email there.


Hi James, I sent you an email at this adress which I found here jedijeb13@yahoo.com. Is this the correct adress? Unfortunately Google+ doesn't work out here (which I don't use either).
NoraStern wrote:
James_Ball wrote:
p.s. I don't really use Google+ but I can be reached at the email there.


Hi James, I sent you an email at this adress which I found here jedijeb13@yahoo.com. Is this the correct adress? Unfortunately Google+ doesn't work out here (which I don't use either).



I haven't been using that one lately but I will check it when I am home tonight.
The past is there to guide us into the future, not to dwell in.
Post a screenshot. It'll help to figure out what's going on
Alexei Gapeev
Millis Scientific, Inc.
gapeev@millisscientific.com
Tel. 877-844-2635
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