Chromatography Forum

Can anyone help me figure out the way of analysing gas compound from airbag and quantification based on the built calibrations done by liquid compound injection? Or I have to prepare gas standard in a same airbag like the sample?

The situation is that I made toluene standard in CS2, and made 1 uL injection. It is 322 uL when it is injected in jection port using HP Pressure/Flow Calculator. A calibration curve can be obtained for toluene with the knowm amount of toluene and the integrated area obtained from GC run. Then I injected 500 uL of gas sample from an airbag in which the toluene is present.

If the quantification of the gas sample based on the above calibration curve is given to be 100ug, so a factor of 0.644 from 322uL/500uL is used to correct the raw data of 100ug. The final result should be 64.4 ug (100 x 0.644). Is it correct?

Cheers
Jimmy

Hi Jimmy

Do not use the gas volume calculated by the HP software, because the injector is hot and at higher than atmospheric pressure it is not relevent to gas in a bag at room temp.

You know the mass of toluene in the injection, and the peak area that it gives. Divide mass by peak area and multiply by th peak area from your sample. This gives the mass of toluene in the 500 ul of sample, and from that you calculate the concentration.

There are still all sorts of assumptions and approximations built in, but it will get you into the right concentration range. Then you need to set up a calibration by spiking air bags with concentrations of toluene that span the concentration that you calculated on the basis of the liquid injection.

Peter