ICH Q2R1 suggests three different approaches: visual inspection, signal-to-noise-ratio, or
variability of the slope of the calibration curve (statistical approach). Vial and Jardy, and
Apostol et al., evaluated different approaches for determining LOD/LOQ and concluded
that they generate similar results (Vial and Jardy 1999; Apostol, Miller et al. 2009). It is
prudent to verify LOD/LOQ values obtained by different calculations. If those values are not
within the same order of magnitude, then the integrity of the source data should be
investigated.
The statistical approach is most commonly practiced, and is associated with the use of well
known equations: