[mariosm]

Hi everyone,
I'm looking for a new method development approach or unconventional for GC quantitation method. We have 9 compounds to analyse simultaneously and I'm wondering if RRF (slope A/slope B) can be used for indirect quantitation? The goal would be to light the working standard preparation. For example, we would use an ethanol standard to quantify a mixture of ethanol, acetone and acetonitrile by direct quantitation for ethanol but indirect quantitation for acetone and acetonitrile using their respective RRF. Method would be validated using both calculation technics to prove equivalency but I'm wondering if this uncommon approach was seen in the past and if you have seen reference for this approach.
Regards

[Stepan]

Use of RRF is quite common and often is a standard feature in GC software. For better accuracy you will need to measure all RRF's for your target compounds. The approach works fine as long as calibration is linear when "forced through zero".

It does not work for nonlinear calibration curves:
-if detector is nonlinear (let say ECD)
-when you work very close to the detection limit;
-when concentration is too high and detector response is non-linear.
- Interferences