Chromatography Forum

Hello-
I am very new to GC-MS and so please forgive my ignorance. I want to observe compounds that are eluting with the solvent (I am using DCM). I tried using a fairly low temperature (40°C) to start (holding for five minutes before slow (10°C/min) ramp, but since that isn't working I thought I'd try another solvent- maybe ethyl acetate but I need to introduce a second solvent delay or something so that I can see the low boiling compounds and then turn off the detector while the solvent is eluting. I know this can be done, but I don't know how. Can anyone help?
I don't have a head-space contraption- just auto-liquid injector.
Our Instrument is an Agilent 5975-6850 with an HP-5 column.
Also wondering if you have a recommendation for training resources (aside from online)

You'll need a much heavier solvent than ethyl acetate. Its retention behavior on a 5 phase won't be so different from DCM that it will help you. Perhaps something like N,N-dimethyl acetamide? That's one that's used in headspace analysis for determination of low boilers in polymers by headspace GC. I'd do a quick search of what people do for this application.

I know you can set your solvent delay in the chemstation/mass hunter anywhere in your method that you want. When I've needed it, it's always been up front so I can't tell you exactly how to do that without having the software in front of me.

Try looking in the Timed Events tab in Chemstation and see if EM Voltage is one of the items that can be timed. You may be able to turn it off then back on from there.

What lighter analytes are you looking for in the analysis?