Coming back to: Specificity, linearity, accuracy, precision, range, robustness — with real criteria posts 91–100

Transfer between laboratories: a method can be transferred from one lab to another, but the receiving lab needs to demonstrate that they can achieve the same performance. This requires comparative testing and sometimes small method refinements.

post #91 answers the question as asked. The question underneath it is different.

Why two laboratories may disagree: after validating the same method, they may still report different purity on the same sample due to integration differences, column age differences, subtle differences in mobile phase pH or temperature. This is normal and not a sign that one is wrong.

Coming back to post #91, because the follow-up matters more than the original answer.

Specificity: the method can distinguish the intended compound from related impurities and degradation products. Tested by comparing results on pure compounds, mixtures of compounds, and degraded samples.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

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).

I read post #95 twice before replying, because I had assumed the opposite.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

This follows post #95 rather than contradicting it.

Range: the concentration range over which the method has been validated. Going outside the validated range is going outside the method's demonstrated performance.

On post #95 — 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.

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.