General Requirements

Range.Ideally, linearity should be established from 50% of the ICH reporting

limit to the nominal concentration of drug substance in the sample solution (for

area percent method). If the linearity does not support such a wide range of

concentration, determine the linearity from 50% of the ICH reporting level to

150% of the proposed shelf life specifications of the related substance (for the

high–lowand external standard methods) as a minimum.This will ensure a

linear response for related substances at all concentration levels to be detected

during stability.