Reproducibility GCMS (GCMS-QP2010)

[Ron]

A few more thoughts, the event time is actually very short for th column you are using, using a longer event time will give you more dwell time on each peak, and may help a little on precision. You may also want to put in a Micro Scan Width of 0.10 or 0.15 amu, this sometimes improves precision. You mentioned that the Detector Volage is set Relative to Tuning Result. What numerical value is entered? The typical value is 0.00 to 0.20.

Finally, how often is the instrument being tuned and is it being tuned with or without mass pattern adjustment?

You should also check the autosampler parameters. The viscosity delay defaults to 0.2 sec, which is shorter than I like. I prefer a 1 sec delay. All the syringe speed parameters should be set to High. Be sure and click on the Advanced button and check the injection port dwell time. The default is 0.3 sec, which can be an issue. I prefer 0, or if doing splitless injections at low concentration 1 to 2 sec.

[Ron]

A few more thoughts, the event time is actually very short for th column you are using, using a longer event time will give you more dwell time on each peak, and may help a little on precision. You may also want to put in a Micro Scan Width of 0.10 or 0.15 amu, this sometimes improves precision. You mentioned that the Detector Volage is set Relative to Tuning Result. What numerical value is entered? The typical value is 0.00 to 0.20.

Finally, how often is the instrument being tuned and is it being tuned with or without mass pattern adjustment?

You should also check the autosampler parameters. The viscosity delay defaults to 0.2 sec, which is shorter than I like. I prefer a 1 sec delay. All the syringe speed parameters should be set to High. Be sure and click on the Advanced button and check the injection port dwell time. The default is 0.3 sec, which can be an issue. I prefer 0, or if doing splitless injections at low concentration 1 to 2 sec.

[bobjakobs]

Sorry for the absence, but I have been struggling with the GC-MS. After trying some more of the suggestions given in this forum (without much success) I turned to the analytical team with some more specific issues that were out of my 'comfort zone.'
It turned out that they were pretty upset about me asking questions on this forum, so the way to a solution came to a dead end there.
Now, I switched to GC-FID, and it does the perfect job for me.

So thank you all for your help and my apologies that I can not tell you what the eventual problem was.