Linearity study clarification

[SRINIVASAN]

can we need include 0% concentration while performing regression analysis? for example i have performed linearity study by using 50ppm, 75ppm, 100ppm, 125ppm and 150ppm(50 to 150% of target). i have calculated slope and intercept by considering these five measurement(n=5). if we consider 0ppm for calculation n=6, pls suggest me for better clarity.. thanks for your time..

[JGK]

It depends on why you want to include the zero point.

If you are only quantifying between 50 - 150% of target why do you need it?

Any result that far away from target would be regarded as "out of specification" (OOS) and would need repeat confirmatory work. It could be labelled as < 50% of target just as easily.

In regulatory environments, blanks are run (and assessed qualitatively) but not included in calibrations as there is no way accuracy data can be calculated and tolerances set.

[SRINIVASAN]

thanks jgk..

i got clarified, and i need clarification for in the case of degradation products ? (usually 0-200% of specification level we will perform to establish the LOD and LOQ)