Topic summary

Reconciling a label claim with a content assay

Analytics › COA interpretation documentation quality amino acid analysis reference standards certificate of analysis batch & lot numbers Closed

This is a generated summary. It shows the 5 most-liked posts from a topic of 7, 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.

i.lehtinenTL2 Moderator8 Aug 2025#2

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

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.

4 likes 12mo

forest_plotTL3Evidence synthesis28 Sep 2025#3

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.

12 likes 10mo

e.steinerTL2 Moderator13 Nov 2025#4

What fields matter on a certificate: lot number matching the vial, test date, the analytical method stated specifically, the measured result as a number, and the acceptance limit stated separately. A certificate missing any of these is weaker.

26 likes 8mo

f.haddadTL2 Moderator4 Feb 2026 · edited#6

Coming back to post #4, because the follow-up matters more than the original answer.

Endotoxin testing is separate: a certificate of purity says nothing about endotoxin. A chemically pure preparation can carry a clinically significant endotoxin load. If endotoxin matters, it needs to be tested and reported.

7 likes 6mo

unit_conversionTL3Regular15 Mar 2026#7

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.

18 likes 4mo

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This topic was referenced in

A certificate with no method stated: what can you conclude?Analytics › COA interpretation · 57 replies
"Greater than or equal to 99%" as a specification rather than a resultAnalytics › COA interpretation · 146 replies
Which fields on a certificate actually matter, rankedAnalytics › COA interpretation · 29 replies

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