An inter-laboratory comparison on one lot, tabulated — what changed since

post #2 is right about the mechanism and I think understates the practical bit.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

post #7 answers the question as asked. The question underneath it is different.

System suitability: injections run at the start of a batch to establish that the instrument and column are performing. Acceptance criteria typically include replicate precision (RSD ≤2%), peak tailing (0.8–1.5), theoretical plates (>2000), and resolution (>1.5).

On post #14 — agreed on the reasoning, with one qualification.

Limits of detection and quantitation: LOD is the lowest concentration that produces a signal above background. LOQ is the lowest concentration at which the method meets precision and accuracy acceptance criteria. Both are determined empirically.

I read post #19 twice before replying, because I had assumed the opposite.

Stability-indicating method: one that can separate a compound from its degradation products. Critical for assay methods that claim to measure actual degradation (as opposed to purity, which is orthogonal).

Accuracy: the method measures what you intend to measure. For purity methods, this is tested by spike-and-recover experiments: add a known amount of impurity to a sample and measure whether you recover the added amount.