Chromatography Forum

I've had some samples recently that were a mixture of low and high boiler/ high MW compounds. Can anyone give me a rough upper limit for either MW or boiling pt? I know the boiling pt in theory needs to be ~50 oC lower than injection temp but I didn't know how firm this was.

Thanks

You have to remember that it is not merely a factor of MW but volatility. Some high MW chemicals can be derivatized and GLC thus can be performed.

Also concentration is an important factor to consider. Trace amounts of a high MW compound may elute quanitatively while more concentrated amounts may not.

Hexacontane is commonly analyzed by GC but even heavier hydrocarbons have been reported. I cannot find its boiling point, only a melting point.

Yet if you try to chromatograph oxalic acid as a free acid, good luck !


I hope this is helpful.

Rod

The column has a major effect on the columns that can be analyzed. I have done hydrocarbons with more than 100 carbons on a short column with a thin phase, but this would be a terrible column for Freons. There are columns that separate light gases extremely well, but are too retentive for compounds as heavy as hexane. There is no simple answer to your question.