Topic summary
Relative retention time as a better inter-laboratory comparator — does this still hold?
This is a generated summary. It shows the 5 most-liked posts from a topic of 16, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.
orbitrap_ola, post #5: 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. Go to post
Linearity: the detector response is proportional to compound concentration across the working range. Demonstrated by running standards at multiple concentrations and showing R-squared values typically ≥0.99.
On post #5 — agreed on the reasoning, with one qualification.
Forced degradation studies: deliberately stress the material with acid, base, oxidant, heat, light to generate degradation products and demonstrate that the method can separate them from the parent peak. Acceptance is that the method is stability-indicating.
27 likes 23mo
e.almeida, post #1: Relative retention time as a better inter-laboratory comparator — does this still hold? I have a specific reason for asking rather than idle curiosity, and the context is below. A documentation question rather than an analytical one. I have a certificate in front of me that reports a purity figure, names a technique, gives a wavelength,… Go to post
Worth separating two things that post #8 runs together.
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.
f.wojcik, post #14: 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. Go to post
Two things before anyone answers the substance.
First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.
Read the full topic (16 posts)
This topic was referenced in
- Why one laboratory's 98.4% and another's 96.1% may not contradictAnalytics › Method validation · 37 replies
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