GC-MS RIC versus Quant. Ion

[clatoz]

I am running a headspace GC-MS method similar to USP <467> for the analysis of volatile solvents in a polymer. When processing the data I get very different results depending on whether I use the RIC (reconstructed ion current) versus the Quant. Ion (m/z=73 for Methylethylketone). I am using external calibration with 3 calibrants. The results are 73 ppm MEK with RIC and 205 ppm with Quan. Ion m/z=73. Does anyone know how to explain this? Is there any guidelines for using RIC versus Quan. Ion for quantitative results?

Thanks in advance.

Regards,

Chris

[Victor]

In the RIC mode the detector acts as a universal detector. It is possible that something is co-eluting with your analyte which will affect the results. In the SIM mode it is possible that this co-eluting substance becomes invisible to the detector, so you may get different results.

One more thing- I don't understand why you are looking at 73- is this a typing error? The MW of your analyte is 72, which means you would be looking at the carbon 13 isotope peak of the analyte!!!!