Chromatography Forum

new to the world of gas chromatography! Looking for advice on the buying the best gas chromatograph for analyzing gas refrigerants particularly R-22. I see used systems on ebay and cost is a factor does anyone have any suggestions? I would need a system that could analyze and give me a breakdown on the refrigerant and what is in it or mixed with.

I would say GC-MSD (mass spectrometry detector). Without such detector, you'd need reference standards to match up retention times of any non R-22 peaks. For example, R-12 gives a nice ion at 85; once about 15 years ago I was asked to identify the contents of a small unlabeled cylinder, and used GC-MSD to establish that it was R-12.

With MSD, you can build your own search library of refrigerant agents and related/suspected contaminants. With MSD you'd only need helium carrier gas, would not have to mess with air and hydrogen for an FID detector. And ECD is only helpful for trace levels of halogen-containing materials, such as refrigerants.

I don't think you's need any cryogenics or anything, could run at 40 °C.

Are you really in Arizona? I would guess one would need refrigeration there !!! It might be of value to fins someone to set up/train you in this field; if you buy a brand-new system, supplier can set up something close to your needs, but new won't be inexpensive.

Thanks so much for your help and suggestion I will look at mass spectrometry detector.

For these compounds I would look at something like the Restek 502.2 column

http://www.restek.com/catalog/view/1470

The 60m x 0.25 Internal Diameter would do a good job of separating refrigerants without needing to cryogenically cool the oven and would be perfect for the mass spectrometer detector.

Something like a used Agilent 6890 GC with 5973 or 5975 Mass Spec would do the job well.

Look up the ARI700 standard from AHRInet for test methods. These (last time I looked) were mainly FID based which is perfectly adequate for QC type of work. Yes you need standards, i used to get them from John Senediak at Intertek in Columbus, OH. The problem with MS (apart form cost and user skills required) is that quantification of a moelcule without a standard is difficult, at least with FID you can use effective carbon number. BTW if the R22 method still has a second method to pin down one impurity (capillary column, subambient), don't bother, you'll never see it anyway.

@ Johnny

Where can I buy the kit they use in CSI?

Ralph

AZ,

Please contact me at aicmm at flash dot net. I would like to discuss this application with you further if you have the time.

Best regards,

AICMM