Analysis of Methanol, Ethanol, and Glycerol in Wastewater

[DWW107]

Hey guys,

This is my first post on the site, and I have a bunch of questions. I was thrown into this project, and know practically nothing about GC's. After many hours on the phone with different companies I decided on the following setup: 5890GC, FID detectors, Equity 5 30m 0.25mm 1.0um (I also have a carboxen1010 PLOT 30m .53mm). I wont name the company, but they went back and forth with me about what I should actually use, so dont feel bad telling me I bought the wrong column. At any rate, here is the problem:

I have samples from a wastewater treatment plant that will have low amounts (between 10-50mg/L) of methanol, ethanol, and glycerol in them. I want to be able to detect these with my GC. Right now the important ones are methanol, and ethanol, so if no one knows anything about glycerol in wastewater samples, that's fine for now.

Here is what I need help with:
1.If I can actually use the column I have.

2.Where to locate methods. (I've searched google and have come up empty, am willing to purchase methods).

3.What kind of standards should I be running? Do I create my own samples than have 5-50mg/L of methanol/ethanol/glycerol and compare them to the peaks I see in the wastewater samples.

Any information would be greatly appreciated.

Thanks.

[chromatographer1]

DWW,

Given your matrix is waste water, ie unknown contaminants, I would try to avoid capillary columns. I know everybody wants a race car on the Interstate freeway but sometimes a 4X4 or even a tank is a better choice when you have to travel cross country over unpaved and unknown roads.

If you try to use the DB-5, use a split mode and try some synthetic samples first to determine if you can achieve good peak results with conditions you chose to use. Use what you have first to avoid spending any more money. I would use an injector temperature of 180° or higher to start and a oven temperature programmed from a much lower temperature. Evaluate and chose what works best with your sample size and concentration range.

My choice would be a Supelcowax capillary or the equivalent from another manufacturer using a SPME fiber and on-column injection.

An inexpensive Porapack Q or a Carbopack B coated with Carbowax 20M packed column could be used as well. This could be fitted with a disposable precolumn when the front of the column becomes contaminated.

Good luck and please let the forum know how it all works out.

Rodney George

[Peter Apps]

A lot will depend on what else is in the waste water. Rodney's advice is (as ever) the way to go.

Peter