Analytics · COA interpretation

Second pass at: Certificates issued by the seller versus by a laboratory

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

s.okonkwoTL212 Jan 2025#1

Second pass at: Certificates issued by the seller versus by a laboratory — setting out what I have, and where I think it stops being reliable.

Two reports on the same lot, and I would like help deciding whether they disagree.

The first gives 96.9% by reversed-phase at 214 nm. The second gives 97.1% by a method described only as HPLC. Neither states the integration convention.

My instinct is that this gap is method rather than material. I would like that instinct checked by somebody who does this for a living rather than confirmed by somebody who agrees with me.

8 likes 18mo

l.krastevTL213 Jan 2025#2

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".

0 likes 18mo

glossary_deskTL3Regular13 Jan 2025#3

l.krastev, post #2: 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". 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 part I am sure of is shorter than the part I have written.

0 likes in reply to #2 18mo

f.piresTL214 Jan 2025#4

Certificates from a supplier's own laboratory are not independent by definition. That is not an accusation, it is a description, and it is why independent submission exists.

Genuinely open to being wrong about this one.

17 likes in reply to #2 18mo

NicolaidesTL3Regular14 Jan 2025 · edited#5

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.

Flagging that the sources on this are thinner than the confidence in the thread suggests.

7 likes 18mo

v.stanescuTL214 Jan 2025#6

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 number is defensible. The precision I gave it is not.

1 like 18mo

aliquot_lineTL3Regular15 Jan 2025#7

f.pires, post #4: Certificates from a supplier's own laboratory are not independent by definition. That is not an accusation, it is a description, and it is why independent submission exists. Genuinely open to being wrong about this one. Go to post

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.

The strength of my opinion here exceeds the strength of my evidence.

0 likes in reply to #4 18mo

e.nilsenTL215 Jan 2025#8

Sensible. I would want the same detail before I acted on it either.

24 likes 18mo

k.bettencourtTL215 Jan 2025#9

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

Noting that the question and the thing people usually mean by it are different.

t.brandtTL215 Jan 2025#10

Picking up post #7: that is the part I would want checked first.

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.

Two people can read the same figure differently here and both be reasonable.

3 likes 18mo

dr_okonkwoTL4 Moderator16 Jan 2025#11

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.

If that is already documented somewhere, ignore me and link it.

7 likes 18mo

m.perrinTL216 Jan 2025#12

Following, with nothing to contribute beyond having asked the same thing elsewhere.

17 likes 18mo

c.cardosoTL216 Jan 2025#13

dr_okonkwo, post #11: 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. If that is already documented somewhere, ignore me and link it. Go to post

Confirming post #11 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.

33 likes in reply to #11 18mo

f.sjobergTL216 Jan 2025#14

0 likes in reply to #2 18mo

orbitrap_olaTL3Mass spectrometrist17 Jan 2025 · edited#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.

11 likes 18mo

i.almeidaTL217 Jan 2025#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.

24 likes 18mo

s.karlsen_rphTL317 Jan 2025#17

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

Post #16 is the version of this I will quote in future. One addition.

Caveat: everything above assumes the paperwork is what it says it is.

n.brobergTL217 Jan 2025#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.

1 like 18mo

customs_ledgerTL3Regular18 Jan 2025#19

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

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.

16 likes in reply to #3 18mo

f.weissTL218 Jan 2025#20

Filing this under things that are true until someone shows me otherwise.

31 likes 18mo

LJankowiakTL3Regular18 Jan 2025#21

Post #19 and I disagree about the size of the effect, not about the direction.

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.

Scoping that to what I have actually seen rather than what I have read.

12 likes 18mo

s.lundgrenTL218 Jan 2025 · edited#22

Fine by me. I had wanted a stronger conclusion and there is not one available.

4 likes 18mo

ambient_draftTL3Regular19 Jan 2025#23

m.perrin, post #12: Following, with nothing to contribute beyond having asked the same thing elsewhere. Go to post

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 in reply to #12 18mo

ak.kravchenkoTL219 Jan 2025#24

Narrowing post #23, because the general version has more than one answer.

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.

Second-hand, so weight it accordingly.

25 likes 18mo

a.kowalczykTL2Regular19 Jan 2025#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.

7 likes 18mo

c.haddadTL219 Jan 2025#26

This follows post #23 rather than contradicting it.

When method identifiers are missing: "reversed-phase HPLC" is less specific than "reversed-phase HPLC at 214 nm on a C18 column with a 10 to 40% acetonitrile gradient over 20 minutes". The second lets someone reproduce the analysis. The first does not.

It reads as pedantry until the day it does not.

1 like 18mo

plateau_notesTL2Regular19 Jan 2025#27

0 likes in reply to #11 18mo

n.vukovicTL220 Jan 2025#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.

18 likes 18mo

o.lindgrenTL2Regular20 Jan 2025 · edited#29

Helpful, and short, which on this subject is harder than long.

24 likes 18mo

n.cardosoTL220 Jan 2025#30

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

Building on post #27 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.

11 likes in reply to #28 18mo

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