Chromatography Forum

Hello all,
We have several problem with our DSQ II GC-MS which are:
1- The background scan spectrum from 10 to 650 is ok.
2- The air/water spectrum from 10 to 90 is ok.
3- The scan spectrum from 50 to 650 is too noisy and unstable, so we could not check very well the spectrum of the calibration gas due to the big noise.
4- All the diagnostics are ok.
5- The RF Auto tune is passed.
6- All other tunes (detector gain, resolution and mass) are failed.

Please note that we make a full cleaning for Ion source, lenses and the anode, and we make cleaning with dry gas of the prefilter and quadruple. Before the cleaning process, we had a noisy background spectrum, but cleaning solve this issue.

You are kindly requested to give me a solution to fix the noise and make the full auto tune.

Thank you in advanced

You say you have cleaned the prefilter with a dry gas.. I assume you mean you have blow it over with the gas but nothing else?

If so I can highly recommed real cleaning of the prefilter.. I have several times seen this part as the main issue with DSQII systems. Just do NOT sonicate the prefiler.. I have tried that and it cost me a new prefilter..

You write you have poor calgas spectra.. What intensity of the calgas do you have? Could be you have run out of calgas?

I would also double check the assembly of the source... I know this is what everyone always says and I am sure you have done it correctly but I see it time and time again that a slight misallignement of the source parts cause strange issues.