GC analysis of monomers

[Amit]

I don't have much prior experience in analyzing monomers by Gas Chromatography. The monomers that I deal with have boiling points in the range of 180 to 200 degree C. Above 140 degree C, these monomers polymerize by thermal initiation even in the presence of an inhibitor like MHQ. Can anyone please suggest me a way to analyze these monomers? I am not sure if the presence of an initiator or MHQ in the monomer samples will be harmful to the column. I am using a capillary colum with a 0.25 micron inside diameter. Thank you.

[Chris Pohl]

Amit,

The polymerization of monomers during GC isn't normally a problem. We use a Perkin Elmer Elite Series PE-1 column. The typical temperature range is 100-350 C.

[Amit]

Hi Chris, Thank you so much for the reply. I tried running some oligomer samples through the GC and had no problems. I am wondering if Benzoyl Peroxide is going to show a distinct peak at, say, 130-160 degree C. The literature states that it melts at about 105 degree C with no reference to any further phase change. Thanks.

[Chris Pohl]

Amit,

I can't say we've ever used GC for analysis of benzoyl peroxide. I don't think it's very likely that this compound will withstand the conditions of GC analysis. You're more likely to be successful using HPLC.

By the way, since you mention oligomer samples, these might potentially create problems with your GC analysis overtime since some of the oligomers may never make it out of the injection port. We haven't ever used GC for the analysis of oligomers so I can't tell you much about the potential risks of that. But perhaps you might want to consider diluting your sample in a poor solvent in order to precipitate the majority of the higher molecular weight of oligomers and thus avoiding injecting them into your instrument.