Chromatography Forum

Posted: **Tue Nov 20, 2007 6:21 pm**

Hi.
First, I'm sorry for my bad english. I hope that you understand me.

I work a MSD 5973.
Two weeks ago, I noticed that the chromatograms was flat.
Then, I executed the autotune, but this did not finish.
I cleaned the ion source and the HED, but nothing changed.
After that, I removed the column and placed a new column.
In this moment, I can execute the autotune, but the results are not good:

EMVolts: 2906
#peaks: 437
Mass 69 precursor: 10.42
Mass 219 precursor: 52.08
Mass 502 precursor: 51.23
Position of isotope mass 70: low
Position of isotope mass 220: low
Ratios of isotope masses: horrible

Can somebody help me?

Posted: **Mon Dec 03, 2007 5:05 pm**

I assumed you checked for an air leak? How old is your electron multipier? What was the emision current when it was last working?

Mike

Posted: **Tue Dec 04, 2007 9:08 am**

Is the PFTBA vial empty?

Posted: **Wed Dec 05, 2007 2:15 pm**

Yes, this is not the problem. Thanks

Posted: **Wed Dec 05, 2007 2:24 pm**

I executed "air & water check", and there are not leaks.
The EM was working good, at 1500 V. I think that this is not the problem.
The emission current is fixed in 34.6.

Posted: **Wed Dec 12, 2007 1:11 am**

If the electron multiplier voltage is at 2906, the multiplier is bad.

Chromatography Forum

Problem with autotune in MSD 5973

Problem with autotune in MSD 5973