Mass calcuation of water and glycol mixtures in antifreeze

[jtcooney]

I am analyzing glycol mixtures used in antifreeze with HP 5890 Series II, using a Sabilwax 0.53mm x 30 m column on FID detector. I am able to determin %glycol with ease, however becasue I am using FID water is not detected. There lies my problem. I can't switch over to another detector like TCD so I am wondering what method would useful in determine moisture content in glycol mixtures after the glycol has been determined by GC. I've tried Rf but the numbers don't correlate well to 100%. I considered Specific Gravity corrections but still do not get a good correlation on low to high blends.

[chromatographer1]

How do you KNOW your glycol numbers are accurate?

If you are having so many problems getting all the numbers to match, isn't that a signal that there might be a concern about the accuracy of your glycol determination.

If all you have are water and glycol in your mix, then how about refractive index against some weighed self made standards?

But that would be too easy and I bet you have dyes and other additives to the mix?, right?

best wishes,

Rod

[Consumer Products Guy]

I'm (obviously) in the consumer products business. And yes, I do have TCD available as well, but wouldn't use it for this. You asked, so:

Choice #1
Do EG by GC, then use Karl Fischer titration for the water content. Don't boo-hoo if your lab doesn't have KF titrator - it should.

Choice #2
Do EG by GC, then do solids content at 105C for at least four hours (like 2 gram sample). You'll lose all the EG and the water, so can determine water by difference.

[aburton]

For moisture content, the best technique would be Karl Fischer titration.

[Consumer Products Guy]

For moisture content, the best technique would be Karl Fischer titration.

I think CPG stated that in the post just before yours.