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Corona CAD and glycols
Posted: Tue Dec 09, 2014 3:49 pm
by H2Oh
Has anyone ever run ethylene and propylene glycol using a corona cad? It seems like it should be well suited to it with boiling points close to each other but quite a bit higher than water and organic solvents.
I asked Thermo about it and they said it wouldn't work, but when asked if they tried it they said they hadn't.
Thanks
Re: Corona CAD and glycols
Posted: Tue Dec 09, 2014 5:04 pm
by Consumer Products Guy
We do glycols routinely by gas chromatography. Either underivatized or as trimethylsilyl derivatives.
Re: Corona CAD and glycols
Posted: Tue Dec 09, 2014 5:41 pm
by H2Oh
Thanks, Consumer Products Guy.
Could you give me some pointers for running via GC? I was running a Restek method with direct on column injections but that suffered from lots of carry over and unstable QCs.
I'd like to be able to reach 1 PPM as a reliable low limit. The best I've managed is around 10 PPM using a Phenomenex wax column that is reproducible and doesn't have too much carry over.
I'm much more familiar with LC so was gravitating away from GC. You're giving me new hope.
Re: Corona CAD and glycols
Posted: Wed Dec 10, 2014 11:00 am
by sbrand
Hi to all
i found the nice (but older) Application Note 301 from ESA (--> Dionex --> Thermo) with the title "Polyethylene Glycols with HPLC-ELSD". As you may know ESA was the developer of the Corona CAD technology. Both detectors are using nebulizer; so i have no doubt, that a Corona wouldn't do the job.
Ask you friendly Thermo Sales Rep for a demo.
Best
Re: Corona CAD and glycols
Posted: Wed Dec 10, 2014 2:14 pm
by H2Oh
Hi Stefan,
I think I saw the same app note! It seemed reasonable to me if PEGs worked, EG/PG would work too. Although looking at ELSDs, it appears I might need to look into the CAD which has lower temp nebulizer option.
Thanks,
Re: Corona CAD and glycols
Posted: Wed Dec 10, 2014 3:52 pm
by Consumer Products Guy
I'd like to be able to reach 1 PPM as a reliable low limit.
We've never looked at levels that low, of no interest to us.
Could you give me some pointers for running via GC? I'm much more familiar with LC so was gravitating away from GC. You're giving me new hope.
Underivatized: see USP monograph for glycerin, there's test conditons for ethylene glycol and diethylene glycol contamination/adulteration. The maximum limit in glycerin is 0.1%.
Derivatized: sample into solvent like DMF, pyridine, mix with something like BSTFA to derivatize, use nonpolar capillary, start with oven like 70 C.
Re: Corona CAD and glycols
Posted: Wed Jan 14, 2015 2:55 pm
by H2Oh
Thanks again CPG!