Topic summary

Second pass at: LOD and LOQ: definitions people get wrong

Analytics › Method validation recovery precision & repeatability linearity LOD & LOQ system suitability

This is a generated summary. It shows the 7 most-liked posts from a topic of 52, 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.

IMainwaringTL3Regular17 Aug 2025 · edited#4

s.poulsen, post #1: Posting this under the heading it deserves: Second pass at: LOD and LOQ: definitions people get wrong Everything below is what sits behind that. Something about LOD and LOQ does not reconcile and I would like a second pair of eyes before I decide which half is wrong. Two sources, both reputable, giving figures that cannot both be right… Go to post

Where the LOD and LOQ discussion usually stalls is that nobody wants to say "I do not know" and everyone is willing to say "it varies". Those are the same sentence with different clothes on.

30 likes in reply to #1 11mo

j.cabreraTL221 Aug 2025#9

IMainwaring, post #4: Where the LOD and LOQ discussion usually stalls is that nobody wants to say "I do not know" and everyone is willing to say "it varies". Those are the same sentence with different clothes on. Go to post

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.

31 likes in reply to #4 11mo

c.serranoTL224 Aug 2025#13

The limit of quantitation determines what the impurity table can honestly contain. Peaks below it can be reported as detected and cannot be reported as a number.

The honest answer is that it depends, and here is what it depends on.

26 likes 11mo

HHidalgoTL2Member29 Aug 2025#20

Where a pharmacopoeial monograph exists, a method that follows it inherits a great deal of assurance. Almost nothing discussed here has one.

Correct me on the arithmetic if it is wrong; I would rather know.

27 likes in reply to #4 11mo

k.redgraveTL2Member2 Sep 2025#27

Bookmarking this. I will come back when I have something worth adding.

26 likes 11mo

OTeixeiraTL3Regular4 Sep 2025#31

Whatever the answer on LOD and LOQ turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, invite the correction.

30 likes 11mo

endpoint_marginTL2Member6 Sep 2025#35

Post #31 put the caveat in the right place and I want to underline it.

LOD and LOQ was covered in the wiki last year and the page has a review date on it, which is a better starting point than my memory of a thread.

22 likes 11mo

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When to suspect the method rather than the sampleAnalytics › Method validation · 115 replies

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