So, i m working during last month with GC-MS. When i'm making the extraction of samples e.g. PAH samples, i'm pipetting significant concentration of two internal controls into the solution. When i will reach the interpretation step, i have to use their areas and its concentration into the calculations to obtain my final result for each sample?
Thank you in advance,
Kiriakos
If you are adding controls prior to the extraction step these are known as surrogate standards. They help you assess the efficiency of your extraction procedure. You would need to set up a calibration for each of them just like you calibrate for your analytes (PAH, in this case). If you are adding the controls after all of your sample preparation steps but before your injection into the GC-MS then these are internal standards. You use them to correct for variability in the GC-MS responses.
Typically you calibrate your compounds corrected for the response of the internal standard (IS), and all samples, standards, etc get the same concentration of internal standard, so (Area compound/Area IS) plotted against (concentration compound/concentration IS) will become your calibration. The slope of this plot is typically referred to as the relative response factor (RRF); if you assume a linear response (I never do) you can simplify the equation to get to the standard RRF equation of Analyte conc = (analyte response * IS conc.) / (IS response *RRF).
- Badges
- Science topic