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Loss sensitivity on HP 5973 Mass

Posted: Thu Oct 23, 2014 9:13 am
by babsnsn
Hi everybody, I'm writing here because I found this forum really useful and hope you can help me. First of all sorry for my bad english!
I recently had a problem on my 5973 MS: after a routinary cleaning of ion source, I tryed doing the autotune as usual and I had a problem of corrupted file, so I loaded an old one that I knew it was correctly working and it seemed to be all ok.
The problem is that, when I start my analysis (4Methyl imidazole on balsamic vinegar) in SIM mode, I do see the internal standard but can't see the 4MeI!I also thought it could be a standard problem, so I bought a new one but nothing changed.
I did a different analysis (glicols) and the areas of the standards newly prepared correspond to the expected values that I obtained in previously calibration....
what can be the cause of this problem? Which test do you suggest to verify the effective functionality of the MS spectrometer?
I'm really upset because I can't understand where the problem could be! I never did a manual tune but I dont' think this could be the problem because, in my opionion, if the mass doesn't work, it doesn't work everytime and not only with some substances... no analytical changes in the method, no change of ramp temperature, column, flow, I did in the past the same analysis and every time worked great... could the column have completely lost the affinity for this substance? I can do a change with a similar column (FFAP instead CPWAX) and do another test meanwhile I wait for some help from you all.
Every suggestion will be really helpful.
Have a nice day to everybody and thank you very much.

babs'

Re: Loss sensitivity on HP 5973 Mass

Posted: Thu Oct 23, 2014 9:33 am
by kubowicz.tomasz
Hello

After autotune you should save new autotune file (I don't know why you loaded old one). You can paste autotune report here (it'd be handy to see it).
Did you make SIM calibration after maintenance?

Regards

Tomasz Kubowicz

Re: Loss sensitivity on HP 5973 Mass

Posted: Thu Oct 23, 2014 9:35 am
by Peter Apps
If you are using full scan to analyse the glycols then you probably have a poor mass calibration that is putting the methylimidazole ion outside the SIM window.

Have you tried re-tuning the MS after you loaded the older tune file ?

If you are stuck with the old tune file for the present then you could try making the SIM window wider as a troubleshooting exercise.

Peter

Re: Loss sensitivity on HP 5973 Mass

Posted: Tue Oct 28, 2014 11:07 am
by babsnsn
Hi everybody, I tried doing another tune but the problem seems to be more simply: the column lost her affinity with the substance!
I did a test with another column and the mass works good... I have to buy a new column, that's all...
thank you anyway for your suggestions.
Have a nice day

babs'

Re: Loss sensitivity on HP 5973 Mass

Posted: Tue Oct 28, 2014 11:12 am
by Peter Apps
Thanks for the feedback. Before you install the new column you need to find out what destroyed the old one, or you will destroy the new one also. Check for leaks and make sure that you have working scrubbers in your carrier gas line.

Peter