ethylene glycol extraction/derivation

[twranger]

hello,
I am currently analyzing water samples for ethylene glycol in an environmental lab, and having the usual chromatography problems (direct inject, wax column, FID), but able to see to about 10ppm. We now have a proposed state permit level of 13 ug/L. Is anyone aware of a method to extract/distill ethylene glycol from 1 liter of water at trace levels?
I have seen procedures to derivatize glycols for GC analysis, any suggestions for going this route? Any way to derivatize a large volume of water and extract the glycol from there?
Thanks for the help!

[tlahren]

Better off extracting the glycol into an organic solvent (e.g., Liquid-liquid, or SPE to organic) and then do the derivatization (MSTFA or BSTFA) in the organic solvent.

[twranger]

That's the problem, ethylene glycol does not extract out of water as other organics (too polar).

[tlahren]

Check these SPE cartridges out:

http://www.sigmaaldrich.com/content/dam ... s-2010.pdf

The same method further developed for better efficiency of ethylene glycol by the EPA:
http://www.epa.gov/region6/qa/presentat ... ecil-p.pdf

This should work for what you want to do.

However, if you are going to use a TMS derivatization technique you will need to evaporate each sample to dryness and reconstitute in ACN preferably. MSTFA/BSTFA will silanize any water left in the sample and you will get this weird insoluble "ball/droplet" of O-TMS-water.

Otherwise I think some people analyze glycols on wax type columns or other polar columns. TMS derivatization works if you want to inject on a non-polar column like a DB-1 or DB-5 or other predominantly methylsiloxane column.

[twranger]

Yes, we are going to try those cartridges, but I'm not impressed by the recovery or small volumes, which limit the reporting level.
Also may try going to dryness/reconstitute route.