Discussion Category: GC-Tandem MS
unsuccessful autotune
Dear Frinds,
I tried to tune the system manually.
from the last autotune the multiplier voltage was very high (2,358)
I reseted the multiplier without installing a new one and I didnt know how to encrease the voltage again.
so on the voltage 1200 I could see only the amu of 131 not any higher value (I couldnt see 219 or higher at all).
so do you think its only multiplier problem or I should do sontheng else.
this results after a good cleening for the ion catridge and ion guide.
please help.
regards.
Fayez
Reply byDear Fayez,
it would be very helpful if you could tell us at which part the auto tune fails. 2350 is extremely high setting. 1200 is too low, around 1800 is a good setting for a 3-4 years old multiplier (manual tune page, increase the detector gain setting). Probably the multiplier is the issue but since it is very expensive you have to be sure that everything else is working properly and the ion source has been assembled correctly after cleanining the system.
I am sure that you have checked the cal gas vial, the cal gas valve, the cal gas tube is in its place and that you have no leaks.
Good luck
Reply byHey Dim,
thanks a lot for your reply.
I put the gain to the max: 5xE6.
I want to share with you some screen shots, pleas send me your email to do that, or send me me to : info@bio-leaders.com
I refilled the calibration gas and checked it well.
for the daily tune its start good with 69 and stop with the message of: could not determine 219.
for the default tune: could not find initial peack ( because its reseting the gain to the lowest).
regards.
Fayez
Reply byHello Fayez,
if i am not mistaken it looks for m/z 100 and if it fails it stops. If you are sure that you have assembled the source correctly, and since the system had been working with the multiplier set at 2350 before you clean the source, then a goog guess is to replace the EM. Even if it is not the actual problem, you would have to change it eventually.
Best regards,
Dimitri
Reply byThanks Dimitri,
I will install the EM and let you know
Reply byHello Dimitri,
I installed another EM.
the signal is better now,
EI Default Tune : Failed , unable to find initiial peak.
EI full tune: Failed, Q1 voltage is very low.
Daily Tune: Failed, Unable to find resolution setting for mass 219 at scan rate 1000.
from manual tune I could see the peaks 69, 131, 219 with max intensity of : 5E+O4
how can I raise the intinsity ?
I'm thinking to replace filament
please advise.
regards.
Fayez