as a part of my school project, I'm analysing chlorinated paraffins (CP) in cooking oils. We are using GCMS for this (after extraction and cleanup steps). I have a question concerning quantification. After the analysis, we obtain peaks that we integrate for knowing the area and for determination the concentration of CP in the oils. During the last steps of calculation we are dividing the sum of all areas for one CP congener by the area of PCB that was present in our Syring standart,we were adding to the samples before the instrumental analysis. My question is, why are we using PCB? I'm little bit confused because for the quantification of our verification I should calculate with the area of HCH (also present in our syringe standart) instead of PCB. I think I don't understand the basic meaining of this methode. Thank you for any answer.