GC method for Nitrous Oxide

Chromatography Forum: GC Archives: GC method for Nitrous Oxide
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Michael Williams on Thursday, November 8, 2001 - 05:35 am:

Greeting fellow Chromatographers!!! I am a forensic chemist seeking advice on a method for the analysis suspected Nitrous Oxide. We have obtained a Nitrous Oxide standard from our local gas distributor. I am Currently using an HP GCMS (model 5890 GC and model 5970 MSD).Since we are attempting to obtain a spectrum of a gas, we are using a hamilton gas tight syringe to collect the sample.We also are using a relatively "cool" injection port ( 65 degrees ) and oven temperature ( 45 - 65 degrees over 15 min. ). Since Nitrous Oxide is a relatively low MW gas, we set the MSD to scan from 10 to 100 amu and we set the filament delay to 10 seconds. Thus far, after injecting ~4 ul of gas we get an error message. I believe we are overloading the detector with sample. Perhaps a smaller injection size or a cooler oven may help. Maybe the interface is too hot (280 degrees).
Any suggestions or comments would be helpful

Top of pagePrevious messageNext messageBottom of pageLink to this message  By Ron on Thursday, November 8, 2001 - 06:17 am:

What concentration is the nitrous oxide? Although nitrous oxide can be analyzed by GC-MS, I would use an ECD with a PLOT column. An ECD can easily measure background levels of nitrous in air, and should have more than adequate sensitivity for you application. Some older MSs will overpressure with a gas injection, and a 5970 certainly does qualify as older. For gas injections to get a decent peak shape you need to do a split injection. I didn't see if you were doing split or splitless injections, but splitless injection will give very poor results.

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