ICH Q2 — Validation of Analytical Procedures

Q2(R2): the performance characteristics a method must demonstrate before it can be trusted to make release and stability decisions.

Outline and talking points — the full write-up is still to come.

What this page covers

The validation characteristics: specificity, accuracy, precision (repeatability / intermediate precision / reproducibility), detection limit, quantitation limit, linearity, range.
Which characteristics are required for which test type (identification, assay, impurities — quantitative vs. limit, dissolution).
Q2(R2) (2023): explicit coverage of multivariate methods and a stronger link to Q14 — validation as the confirmation of an analytical target profile, not a box-check after the fact.
The tie to Q1: a method used on stability must be validated as stability-indicating (demonstrated via forced degradation).

Worked example: a validation protocol + acceptance criteria for an HPLC assay.
Contrast small-molecule assay validation with a potency bioassay for a biologic.
Decide depth on statistics (regression diagnostics, %RSD expectations by concentration).