Trap current

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

8 posts Page 1 of 1
Dear Chromatographers.

Does anyone know what means this message?


Then the data acquisition stops.

The system is:
GC-MS Shimadzu QP2010, with a VOCOL column.
Emission current: 60uA.
Ionization Voltage: 70V.
This message appears almost always when the column is conected to a DYNATHERM ACEM 900.
And I found a vacuum leak but I do not know if it is the problem.

many thanks.

The trap current is insufficient error message usually occurs when something is blocking the pathway between the top and bottom filament. The blockage could be that the GC column is inserted too far so that it actually goes into the ion source box. It could also mean that maybe the ion source box is installed incorrectly, thus blocking the pathway. There is a feedback circuit that monitors the filament current. If it gets too low, the current is increased until it eventually reaches a maximum. Once it reaches a max, the error message appears and the system turns off the run/tune. We have also seen it when there have been board issues.

Dear Robert. Thanks for your help. So, I have more information. We use this GC-MS sistem to analyse Semivolatiles with another column ( narrower and less flow rate) and a AOC-20i auto injector but the message doesn´t appear under such configuration. Aditionally the message always occurs at the beginning of the run just when the filament is turned on ( solvent cut time 4.5minutes) but after a while say 8 or 9 minutes It doesn´t.
What happened to your probelm friend.....I need to know how you fixed the problem....Now I'm also having the problem in my shimadzue GCMS.... I'm using it without a gas filter.
Dear pathumweerawarna.
So, I think It is a plug of water getting into the ion source, I think this because:

-It only happens in "wet" techniques: Purge and trap, Thermal desorption ( atmospheric sampled tubes, not for standards).
-It only happens at a higher flow rates in a wide bore column.
-It only happens at the beggining of the chromatographic run.
-An aged filament is probably inplicated in the problem.
-It only happens when the filament is turned on.

Based on these I had tried with some success:

-Observe the Vacuum level indicator ( U. vac.) at the begining of oven program and keep the solvent cut time as long as posible ( maybe a new column? ).
-Change old filaments or interchange filament positions.
-Perform a new AutoTuning and Increase, just a little, the emission current.
-Improve the dry estage for P&T and thermal desorption.

good luck.
This can also be caused if the wires inside the chamber are touching. This is an easy check.
If at first you don't succeed... That's what hammers are for!
I have the same problem. I change the filament 2 to 1 and it happend the same problem. This message appear after ion suorce cleaning. Maybe its a coincidence, because the filament has 600 h.
this error message can occur, when a filament gets weak and "hangs through". The filament wire gets bended and the wire is physically out of focus and no more in the correct place.
Try to switch to the other filament. If it works with the other (hopefully newer) one, the bad filament should be changed soon.
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