Signals picked up by scan mode only!!

[doogie]

I have a triple quadrupole. I shot some standards running through a column.
And I see the peaks through scan mode. But, not from MRM mode.
I re-confirmed the MRM parameters by re-tuning. It looks everything is fine.
But, I still don't see the peaks through MRM mode.
I gotta need helps or any ideas.

(I checked out the argon gas)

[Pepter]

MRM so you have set the proper parent ions / collision energy / product ions etc ?

[doogie]

Yeah! I have double-checked them and I actually re-run standards with those ion transitions. I am still scratching my head!

[Pepter]

Which scan mode are you running ? The parent ion scan mode or the product ion ?

The way you write i understand that you scan the mass range of your parent ions than you change to MRM and get no signals ... am i right ?
Or is it product ion scan mode.


Please give some data
Scan range
MRMs




What kind of QQQ is it ?

[doogie]

Scan range: 200 - 500

MRM range:
273 -> 238
316 -> 220
332 -> 314
353 -> 255
380 -> 300
396 -> 298
412 -> 314

I use ESI (+) for ionization.

The instrument is a Micromass Quattro micro API (from Waters).

Got a clue?

[kerri]

Did you try to run full scans using MS1 as well as MS2 (using 0 or minimum collision energy)?

Its possible that your MS2 is either nonfunctional or the calibration is off...

[doogie]

I did MS1 scan (parent ion).
Well, I am not sure that my MS2 didn't work because when I tuned infusing standard by a syringe, I got daughter ions that I expect.
But, I don't see the ion transition peak when the standard go through the column. Makes me more confused.

[Pepter]

Once again.

1) You can see parent ions on scan mode (MS1 Scan ?) when the analytes go through column
2) Cant see any of transition ions from MRM mode when the standards go through column
3) MRM mode and all transitions works fine with manual injection


Do you use the same method for both manual and autosampler injection ?
Is the amount of analytes the same for both injection types ?
All transitions that You list are in one time segment ?

You write that you double-checked MRM by re-run standards with ion transitions... so it was manula injection ?

give us some print screens of your acquisition pan

If you solve the problem also write please sounds mysterious .

[doogie]

Yeah, It is MS1 scan (parent ion scan).


Do you use the same method for both manual and autosampler injection ?
=> Yes, I used same method.

Is the amount of analytes the same for both injection types ?
=> It is hard to say that because Injection volume is 5 uL through column running. And Infusion speed is 10uL/min for manual tunning.

All transitions that You list are in one time segment ?
=> I don't know what this means.

I still have the problem. Since my target analytes are toxic, it is difficult to handle. Anyway, I just want to say thank you. This website is awesome!!

[Pepter]

Woudl be easier if you link us your acquisition pan (if its possible) with MRM settings.

Some printscreen from our machine. Agilent/software MassHunter
http://www.voila.pl/197/drb32/?1

Left side - you have liste of time segments.
from 0 to 2.5 minute all garbage running to waste dosent reach my MS
from 2.5 to 6 minute i catch the ions that iam interested in
than from 6 minute up to 12 once again i swich to waste.

Can you run any other non-toxic analytes ?

[doogie]

Oh! I got it.
I have three segments.
First and second segments have all MRM modes. (6-14 min and 14-20 min)
Last segment has scan mode (20-30 min) this is actually not used for analysis).


No, I don't think so. Those are all toxic no matter how strong or weak.

[Pepter]

So your method looks like this ?
1) 0 -> 6 (SCAN MODE with range 200-500)
2) 6 -> 14 (MRM 1 - the tansitions that you listed)
3) 14 -> 20 (MRM 2 - the transition that you listed)
4) 20 -> 30 (SCAN MODE with range 200-500)

Check in this way.
Cut off the number 1/3/4 the method will look like this :
1)0-30 (MRM 1)
injection on column.

[doogie]

Yeah! you are right!
That is what I did.
Sure, I can try that easily. But, right now the instrument set up for another experiment. I will try little bit later.
Again, I appreciate your help. Thanks a bunch!!
I will let you know once I am done.

[Pepter]

One more question.
=> It is hard to say that because Injection volume is 5 uL through column running. And Infusion speed is 10uL/min for manual tunning.

How many uL you load to MS/MS during one run of manual tunning ?

This one MRM run shoudl answer the question where you make error.

Cye.

[doogie]

Well, when I do the manual tunning, the syringe infuses continuously. That is why I said infusion speed. I don't know if you are familiar with micromass API. It allows users to provide solution through a syringe that push the solution continuously at low speed like what I used. It is not an injection thing like a shot. During the infusion, users play around adjusting all the parameters to get the optimal result.
I hope I answered your question. Thanks a lot!!