Chromatography Forum

I am working with GC-MS where MS is 5973N. I got a problem while running a sequence. after few injections of sequence, the signal became flat. and then after that i tried to run scan it gives no signal. I checked filament it is OK, MS status also appears Ok, I tried to tune it but it give message, action stopped, gain off is 0 and narrow peaks. I opened MS and observed ion source part was very black, I cleaned it according to standard procedure very carefully, then i re-installed back the Ion source assembly, when I restarted GC-MS it started succesfully, and tune scan showed nice peaks, but it is not working again after few moments,
What can be possible problem?
and how can I check that EMV is working properly.
Because EMV was working previously at 2900 while its upper limit is 3000.
Regards
Murtaza Hyder

I assume the electron multiplier has completely died, which is interesting as I'd usually replace when they get to around 2700 volts so can't say for sure what an MS does when the electron multiplier is completely dead.

But anyway, replace the multiplier.

Could be the multiplier - or not.

The fact that the instrument failed, started running after cleaning and then failed again would lead me to step back and look again. There might be a loose connection that has opened. It is a bit more difficult to get a short in a '73, but be sure the leads are in good shape and there is nothing close to touching anythign it should not.

What diagnostic information is there? Vacuum reading? Are all voltages in the source where they are supposed to be? Are all connections tight. Any indication of anything shorting out?

Yes vacuum is OK it is 1.5 ' 10E-6.
I do not know how to check voltages in source.
and i am sure connections are tight.
It simply can not tune and says could not get peak width stable, or very narrow peaks.

Could be the multiplier - or not.

The fact that the instrument failed, started running after cleaning and then failed again would lead me to step back and look again. There might be a loose connection that has opened. It is a bit more difficult to get a short in a '73, but be sure the leads are in good shape and there is nothing close to touching anythign it should not.

What diagnostic information is there? Vacuum reading? Are all voltages in the source where they are supposed to be? Are all connections tight. Any indication of anything shorting out?

Yes vacuum is OK it is 1.5 ' 10E-6.
I do not know how to check voltages in source.
and i am sure connections are tight.
It simply can not tune and says could not get peak width stable, or very narrow peaks.

Idea's

If your peaks are too narrow, it simply means that the MSD cannot see the peaks for the tuning solution.
Though I would say that the voltages for your EM are very high, I would not speculate that as to being the reason why you cannot tune. If you can see acetone, then the horn still works.

1. How did you clean the source? say if you used the Al2O3 powder to scrape this off, but did not sonicate the pieces long enough, this could yield a tuning issue. especially in the upper m/z.
2. are you out of tuning solution? can you inject acetone and the sensitivity is fine but you still see no solution?
3. can you see air if you scan?
4. Have you switched filaments?

good luck.

Thank you very much,

I cleaned with Al2O3 and I sonicated it in Methanol first for 2 hours and then in acetone for half an hour.
The tuning solution tube has solution though it is not full it is almost half the tube.


should i inject the acetone to see its spectrum like normal analysis or what?

when I scan some time it say no peak found, some time it is giving strange peaks of various masses, but not constant.
Yes , but filaments are working and they are almost new.

regards

On the sonication, I would focus on the washings as well. You could sonicate for 15-20 minutes a time for about 3 times in MeOH and 3 for acetone.
Just because your MSD cannot tune does not mean there is a problem with the filaments or horn (though the horn should be replaced if it is indeed that high in EMvolts). Depending on the column you have you might want use something else. MeOH and Acetone are the basics.
The other thing I would look into is ramping the lenses under "manual tune" and the "ramp" tab. If the results yield something all over then there is a possibility that one of the lenses is shorted (something very easy to do) to the source chamber. (this has occurred to me)
Results of this are the tuning values cannot be reached because or sometimes 69 m/z can still be seen but the other two will not be seen.

Good luck

hello willnatalie
What do you mean by shortening of one of lens and if it is shortened how would i come to know , i mean whatt should i expect, when i rap lens?
Reagrads
Murtaza

http://www.chem.agilent.com/Library/use ... 035256.pdf pg 204 and 206.
The little tabs stick out that connect to the orange and blue wires could be touching the source body. It could also mean the the wire is not snug on the tab (my problem) the orange wire was loose.
If there is a short the graph will show lines all over (up and down, up and down), not a nice curve.
Before you take everything apart again, did you go back and use a previous tune file that did work? I'm assuming you did nothing to the column.

Hi smsmurtaza,

Have you managed to solve this problem? We've been having a similar problem and I'm intrigued to see what caused your problem?

Hello every one

Thank you all for your nice suggestions. I have managed to tune MS. It was a problem with Ion source, and Quadrupole. First I cleaned Ion source, according to instructions given in manual. But i could not manage to tune it. Then i observed it carefully and i saw some black spots inside Quadrupole. So I cleaned quadrupole as well.
and then i was successful in tuning.
Now it is working properly.
Thanks again to all.

Regards

Murtaza Hyder

Hi,

Our Agilent manual says not to touch or clean the Quad, that an Agilent tech needs to be called in to do this. Did you get someone in or did you do it yourself? How did you clean it?

Thanks!

Hello

I did it by myself, took it out and soaked for some time in methanol, then, carefully removed black spots using methanol and cotton swab. I do not know about that, so i did it by my self.

Thanks

Murtaza

They can be cleaned by the end user if you are careful. Methanol will work, but I have better luck using hexane to clean them.