High molecular weight compound analysis using GC-ECD

[rukkiram]

We have one fluro-substituted compound. The molecular weight of the compound comes around 1000. Is it possible to analyze the compound in GC-ECD? What is the maximum molecular weight we can analyze in GC? Thanks in advance your help.

[HPLC chemist]

There is no MW that cannot be analyze by GC. However, GC requires that the molecule be volatile which decreases as the MW increases. You are more likely to analyze the molecule with HPLC if it can be solubilized (I analyzed the peptide Oxytocin which had a MW of 1007 daltons).

[rukkiram]

Thanks for your response. I am also thinking of moving to UPLC. Some articles are saying you can analyze some alcohols by derivatizing it with Heptafluro derivatives. The derivatizing process going to increase the molecular weight. I was wondering how high we can in terms of molecular weight we can go. Most probably I will analyze them using UPLC.

[Rndirk]

Thanks for your response. I am also thinking of moving to UPLC. Some articles are saying you can analyze some alcohols by derivatizing it with Heptafluro derivatives. The derivatizing process going to increase the molecular weight. I was wondering how high we can in terms of molecular weight we can go. Most probably I will analyze them using UPLC.

Derivatization of alcohols and acids for GC (for instance esterification) will indeed increase their molecular weight but increases their volatility. It lowers the intermolecular forces. There is no easy relationship between MW and boiling point unless you're talking about a series of linear alkanes.

There's no simple rule whether something is more suitable for GC or HPLC, or both. Check literature or application notes how others do the analysis of yours or similar compounds.

[rukkiram]

Thanks for your response. I will do some literature search on this analysis.

[Peter Apps]

We have one fluro-substituted compound. The molecular weight of the compound comes around 1000. Is it possible to analyze the compound in GC-ECD? What is the maximum molecular weight we can analyze in GC? Thanks in advance your help.

Unless it is perfluorinated an ECD (as in electron capture) will not give much more signal than an FID. With a MW of 1000, even with no sticky functional groups you ate not going to be doing this with the usual columns and conditions.

Peter

[rukkiram]

Thanks for your response.