Chromatography Forum

First of all, thanks for all the great info here. My question is concerning percent analysis of a certain binary mixture. As an example, a customer is having application problems with his/her gas mixture which is suppose to be 75% Argon and 25% CO2. Well, I analyze the gas via my Varian CP-4900 Micro Gas Chromatograph. At this point is it possible for the software to give me a percentage reading as opposed to an area (count)? The columns that I am using are: Pora Plot Q 10mm and Molecular Sieve 20mm. Any and all input are greatly appreciated.

First thought that comes to mind, rather than asking someone you don't know through the internet, would be to call Varian Customer Service or your local sales rep and ask them.

best wishes,

Rod

It would be useful if you would mention what Datasystem you are using. Most likely Galaxie. I do not have much experience with this system yet but most likely the story below can also be applied to Galaxie.

What you ask should be possible with any datasystem connected to the 4900.

In the case you would use EZChrom or Maitre (the Varian version of the same CDS) there would be 2 proper ways.

- NORM% which would take the calibrated concentration of both peaks and normalize everything to 100%. i.e. the total concentration of both peaks is always 100%.
- ESTD Concentration. After proper calibration also here the results will be close to a 100% but depending on the differences between your calibration sample and your unknow sample, one measement may total to 99.5% for both peaks combined where the next measurement will result in a total of 100.5%.

Both methods are adequate.

If you don't want to calibrate you can still do the above and use Manual RFs in the Peak Table or use Area% which will assume the RF's of both peaks are about the same.

Basic chromatography really.

JW