Sensitivity/Signal Level

The first thing I would recommend is to run an air/water check as well as a standard spectra autotune.  This is to ensure that the system is properly pumped down and free of leaks as well as ensuring that the MS is functioning properly. If there are no leaks (28<10% at most), water has been baked off (18<20% at most) and running a standard specra autotune meets criteria, then I would start looking at possible GC and or pyrolysis issues.

Dan

Air and water are low as they were pre-source cleaning. System is leak tight (confirmed several times now). Autotune is similar to previous tunes. This is a good example of why you don't fix something that ain't broke. The calendar said it's time to clean the source.....now the instrument is an expensive boat anchor!

What GC and pyrolysis issues do you think should be investigated?

Next step would be to make a liquid injection of a known mixture that you have preferably run before to establish that the GC is functioning correctly.  Once that is done, I would move on to the pyrolysis unit.  I know it seems like taking minor steps but in order to efficiently troubleshoot a complex system you have to systematically eliminate each component.

Dan

I would make a quick check that the column is not broken close to the inlet, probably not as you are not seeing elevated nitrogen levels, but it doesnt hurt

Dan