acetone problems

[shekharbadam]

hello
we have 2 gc-ms instruments. In one of gc-ms, i can see diacetone alchohol, mesityl oxide in the background after running acetone blank. I ran some acetone balnks on other gc-ms, but i didn't see any. I changed retention gap, liner, septa, syringe, etc. still, i can see those in the background. I dont know where those are coming from? Help needed

[Don_Hilton]

With the comparison between two instrument. Do both have the same column (stationary phase and dimensions), the same inlet configuration, including liner. If the diacetone alcohol and mesity oxide is actually present in the acetone sample, is the instrument that did not see these capable of seeing them?

Assuming two instruments configured the same way and with the same sensitivity:

What happens when you make a blank run by pressing the run button without actually making an injection. Assuming that such a run is clean, are you using an autosampler. If so have you cleaned out the wash sovent vials and filled them with fresh solvent?
Still assuming an autosampler - cap an empty vial and run it as a sample. This involves every part of the system except the sample.

[ods-at-pacific]

I have a few questions about your message.

What is the GC column (length, stationary phase, film thickness, length and diameter) and what are the GC conditions (carrier gas, flow rate and linear velocity, injection type (split/splitless) injector temperature column temperature (isothermal or programmed; if programmed, what is the program)? What is the temperature of your ion source? What type of m/z analyzer are you using and what is its temperature?

When you say that you see diacetone alcohol and mesityl oxide in the background, what do you mean, i.e., do you see peaks in all the mass spectra that represent the various ions of these compounds, or do you see GC peaks that are made up of the spectra of these compounds? When do you see this background; right after and inject of a standard, unknown sample, etc.? Or do you see these compounds as chromatographic peaks after you inject acetone?

Thanks