UV detector used in LC is an absorbance detector and when reaching saturation points will not be linear in response.
FID (you did not mention this LITTLE bit of information in your question) is a detector which can be quite linear over 5 to 7 orders of magnitude, but even so, it can be used in such a way where the response is non-linear.
ECD and TCD and others used in GC have limits to their linearity and one should NEVER assume one is working in a range where the measurements are linear.
No one performing analytical chemistry and developing analytical methods will ASSUME their results are accurate. They will PROVE their results are accurate. This is why auditors exist and governments pass laws.
If you don't KNOW your measurements are linear then you don't know they are accurate, right?
Would you take a medication if you thought there was a possibility that the dosage might be in error due to a non-linear response in an analysis by an instrument that had not been shown to be linear? I mean, what's a little overdose going to do, kill your kidneys? stop your heart?
Professionals are supposed to be professional. Do it right, the first time, not after repeating the test when adequate proof was shown to be absent.
I hope your auditor is in house, and not Government supplied. Jail time is no fun if you are a chemist (not that I know first hand).
best wishes,
Rod
