Chromatography Forum

Hi,
I need to analyze industrial gases: N2, CO, CO2, water vapour for MeOH content (max 1500 ppm MeOH). I look for any simple method of makeing gaseous mixtures of MeOH in such contentration range (50-1500ppm) for calibration. I think of permeation method but it seems too complicated. Any sugestions?
I use: Porapak Q and TCD for N2, CO2, CO and water vapour and FID for MeOH analysis, carrier gas He.
Regards

You can purchase gas standard mixtures pre-made in cylinders from Scotty and other vendors that work very well. It is probably not cost-effective or reliable enough to try and make them yourself.

Also you can use Drägger tubes for the analysis of gases, but i think you have to sampling isokinetik method, that is a cheaper and easy way to do it, but clear probably you can obtain better acuracy an precision by chromatography.

Thanks for answers. I want to make calibration mixture in 1l glass cylinder flushed and filled with helium and equipped with 2 valves and silicone membrane. It let to inject known amount of MeOH (for example 1ul), and after evaporation the mixture would be dosed to the injection loop by peristaltic pump. Is it a good way to calibrate GC for gaseous MeOH mixtures (max 500ppm)? Does it make sense?
Regards

You must be careful about mixtures as you describe. You can 'dew' out the analyte of interest if not careful. Warming the container of the sample is usually required and dilution of sample can lead to errors.

A better way would be to use a permeation tube and a heated sample line. This allows you to vary the concentration dependant upon the flow of gas through the sample system.

It is a commonly used method to calibrate process analyzers and is quite reliable.

Do a web search for permeation device or tubes for vendors.