Analytics · COA interpretation · continued

Second pass at: Certificates issued by the seller versus by a laboratory posts 31–60

Analytics › COA interpretation certificate of analysis amino acid analysis batch & lot numbers

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.

PharmNotes_WhitfieldTL4Pharmacist20 Jan 2025#31

glossary_desk, post #3: A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it. The part I am sure of is shorter than the part I have written. Go to post

Where two documents for the same lot disagree, the useful question is which was measured and which was transcribed. Most such disagreements are the second.

This is the sort of thing the wiki should carry and currently does not.

19 likes in reply to #3 18mo

s.mbekiTL220 Jan 2025#32

No disagreement from me. Posting only so the question does not look ignored.

0 likes 18mo

n.abernathyTL3Analytical chemist21 Jan 2025#33

n.broberg, post #18: Where I part company with post #14, and it is a narrow parting. An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is. Go to post

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

2 likes in reply to #18 18mo

f.piresTL221 Jan 2025#34

Collapsed as off-topic by two members at trust level 3 or above

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

k.vanheckeTL221 Jan 2025#35

The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".

26 likes 18mo

v.baptistaTL221 Jan 2025#36

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

Two sources, same conclusion, and I could not rule out that one copied the other.

0 likes 18mo

bench_notesTL4 Moderator21 Jan 2025#37

i.almeida, post #16: A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it. That distinction has done more work for me than anything else in this category. Go to post

Post #35 answers the question as asked. The question underneath it is different.

When a document puts the specification in the result column, it has told you the release criterion, not the measurement. Those are different claims and the second is weaker.

Happy to be corrected if someone holds better data than mine.

4 likes in reply to #16 18mo

a.vukovicTL222 Jan 2025 · edited#38

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

12 likes 18mo

h.ferrariTL222 Jan 2025#39

Adding a note of thanks rather than an opinion. I did not know most of that.

8 likes 18mo

r.villalobosTL222 Jan 2025#40

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

20 likes 18mo

t.pereiraTL222 Jan 2025#41

I had written a reply contradicting post #37 and deleted it. Here is what survived.

The mechanism is plausible, which is not the same as established.

9 likes 18mo

n.nybergTL222 Jan 2025 · edited#42

Confirming post #41 from a second method, which matters more than confirming it from a second person.

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

I am not the right person to answer the follow-up to this.

2 likes 18mo

c.grimaldiTL223 Jan 2025#43

n.vukovic, post #28: An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is. Go to post

Where two documents for the same lot disagree, the useful question is which was measured and which was transcribed. Most such disagreements are the second.

That is the version I use. It may not be the version that is correct.

0 likes in reply to #28 18mo

f.villalobosTL223 Jan 2025#44

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

28 likes 18mo

j.fonsecaTL223 Jan 2025#45

Collapsed as off-topic by two members at trust level 3 or above

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

dr_okonkwoTL4 Moderator23 Jan 2025#46

Post #44 is right about the mechanism and I think understates the practical bit.

Worth reading the earlier posts in this thread before acting on mine.

0 likes 18mo

n.kuuselaTL223 Jan 2025#47

a.kowalczyk, post #25: Worth separating two things that post #23 runs together. An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is. I have left out the parts I could not verify. Go to post

On post #46 — agreed on the reasoning, with one qualification.

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

That is one dataset and I would not build a rule on it.

0 likes in reply to #25 18mo

PharmNotes_WhitfieldTL4Pharmacist24 Jan 2025#48

orbitrap_ola, post #15: An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is. The disagreement above is smaller than it looks once the terms are fixed. Go to post

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

The answer changed when I changed how I was measuring, which was informative.

21 likes in reply to #15 18mo

septum_entryTL2Member24 Jan 2025 · edited#49

When a document puts the specification in the result column, it has told you the release criterion, not the measurement. Those are different claims and the second is weaker.

3 likes 18mo

f.laurentTL224 Jan 2025#50

a.vukovic, post #38: A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it. Go to post

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

0 likes in reply to #38 18mo

MJayawardenaTL3Regular24 Jan 2025#51

Building on post #48 rather than restating it.

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

That matches what I was told, which is not the same as knowing it.

15 likes 18mo

d.nilsenTL224 Jan 2025#52

bench_notes, post #37: Post #35 answers the question as asked. The question underneath it is different. When a document puts the specification in the result column, it has told you the release criterion, not the measurement. Those are different claims and the second is weaker. Happy to be corrected if someone holds better data than mine. Go to post

Not the whole picture, but the part of it I can speak to.

30 likes in reply to #37 18mo

DOdendaalTL3Regular25 Jan 2025#53

Reading old certificates: if a certificate is dated years ago, the lot it describes might be old. That is not automatically a problem but it is worth noting. Fresh testing on the current lot is stronger than old testing on an older lot.

0 likes 18mo

n.zielinskiTL225 Jan 2025#54

This is the first time the answer has come with its own limits attached. Appreciated.

3 likes 18mo

e.dalgleishTL3Regular25 Jan 2025#55

Written in the hope of being told what I have missed.

10 likes 18mo

b.teixeiraTL225 Jan 2025#56

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

22 likes 18mo

s.grahameTL2Member25 Jan 2025#57

k.bettencourt, post #9: The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once". Noting that the question and the thing people usually mean by it are different. Go to post

A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.

0 likes in reply to #9 18mo

r.ilungaTL225 Jan 2025#58

Post #55 describes the usual case. This is about the unusual one.

Take it as a starting point and not as a specification.

1 like 18mo

f.abrahamsenTL2Member26 Jan 2025#59

Amino acid analysis gives content: it hydrolyses the peptide and quantifies the residues. It measures the peptide content independent of chromatographic purity. Very few supplier certificates report it.

6 likes 18mo

ka.haddadTL226 Jan 2025#60

An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.

I am aware this is the third time this month I have made this point.

16 likes 18mo