Glycols

[spaceage]

Does anybody here analyze glycols by GC/FID. We utilize 1 uL aqueous direct injections. Liner is direct connect drilled with hole at top. It still seems hard to avoid mis-injections(by hand). Our samples are well waters high in minerals. It seems difficult to pass ccv at end of run because of matrix problems. We use stablewax column as recommended. Sometimes during calibration we get bad injection where sensitivity is reduced by 50%. A simple re-injection usually solves problem but I am concerned about volatility in the inlet(225C). Peak shapes are great and we can easily see 1 PPM. I here stories of daily inlet maint. and frequent column changes. Anybody done these for awhile and can lend some advice?

[chromatographer1]

Your samples must be some of the most difficult to analyze for glycols.

You are injecting water, which really flashes a large volume at that temperature. And you are adding a variable amount of salt deposits in your liner and column every time you inject. No inert injector or column in your lab !

At least, not for long.

I would expect you to replace your injector daily, and your column monthly or sooner, depending upon the severity of the samples and the number of injections.

Given the ambiguity of your sample description and analytes measured, I would not expect much help. 1ng of 1mg (1ppm) of water is pretty good for EG and PG.

Your description of your results sounds realistic.

To do better, I would derivitize your glycols and that would solve all your problems, but cost you money, but it could save you time.

The forum archives has this topic covered SO MANY TIMES it may be difficult for you to find exactly what you are looking for. But I think you should search them anyway.

best wishes,

Rod

[jdezeeuw]

you may consider to use a hot-needle injection technique. That seems to work pretty good, especially when you cannot use glass wool.

jaap,
Restekcorporation