Chromatography Forum

Hello,

I am using Chemstation for GC to set up an analysis of VOCs. The target list is very long, and I won't have a standard with all of the compounds in it. So I'll need to use a few compounds to calibrate many.

Is there a way to do this in Chemstation? Do I need to create Compound Groups? The online help wasn't very clear on how to do this.

Randy,

I have done this with limited compounds but no standard. As an example, I did this for propylene when I had a standard for propane. The good news is that you can simply insert the compound in the calibration table, name it, assign an amount and assign an area. Viola you are calibrated. There is a multitude of bad news with this approach. First, what is the basis for the area that you punch in? In my case I can use the carbon counting capability of the FID and be reasonably close. Second, in your case, it sounds like you would have to figure out what compound will respond at something close to the same level. Third, and most important, what you really have is an educated guess which you should disclose to your data end-user. In my case that is good enough for the customer (they don't expect to see propylene very often) but it may not be the same for your end user.

Best regards,

AICMM

I assume you are using MS for VOCs. You can use semi-quant which will allow you to relate your target analyte against something else that you have have calibrated.

Rich

I will be calibrating in units of ppbC/ppmC, so I will be using the carbon-counting ability of the FID. This will indeed provide a close enough approximation.

Currently, though, I have the regular Chemstation GC software installed and not the EnviroQuant software.

If I have to copy and paste the levels and responses for all of the compounds for which I don't have a standard, then I think I may need to install EnviroQuant instead.