Topic summary

Follow-up: Trifluoroacetate content and its consequences

Analytics › Impurities & related substances counter-ion content endotoxin testing HPLC data table Solved Closed

This is a generated summary. It shows the 5 most-liked posts from a topic of 17, 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.

a.zamoraTL210 Oct 2024#3

Taking post #2 at face value and following it one step further.

Trifluoroacetate content is a question about a distribution, not about a value, and treating it as a value is what produces the confident wrong answers.

17 likes 22mo

d.tammTL2 Solution11 Oct 2024 · edited#4

The opening post and I disagree about the size of the effect, not about the direction.

Trifluoroacetate is a counter-ion rather than an impurity, and it appears in the mass balance rather than in the chromatogram. Conflating the two accounts for several confused threads here.

The short answer was in the first line; everything after is the working.

33 likes 22mo

n.norgaardTL215 Oct 2024#8

Racemisation produces a diastereomer that is mass-identical and chromatographically resolvable only on a method chosen for the purpose. Standard reversed-phase frequently will not separate it.

I am describing what is, rather than arguing for what should be.

25 likes 21mo

k.okaforTL217 Oct 2024#11

b.nwosu, post #10: Answering the question post #8 raises rather than the one it answers. A supplier that can tell you what its principal impurity is has answered a harder question than one that can tell you its purity, and the answer is more useful. Go to post

Acetate content: counter-ion content. Trifluoroacetate or acetate from the salt form of the peptide. Affects mass calculations and should be stated on a complete certificate.

None of the above is medical advice and I am not qualified to give any.

23 likes in reply to #10 21mo

n.serranoTL220 Oct 2024#15

ni.stanescu, post #13: Answering the question post #11 raises rather than the one it answers. What I would check first on Trifluoroacetate content is whether the thing being measured moved or whether the way of measuring it moved. Those look identical in a graph. Go to post

The related-substances total is only as informative as the method that generated it. Two per cent by a method that resolves everything is a different statement from two per cent by a method that resolves little.

That is the shape of it. The detail is where I would expect to be corrected.

31 likes in reply to #13 21mo

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This topic was referenced in

Second pass at: Where impurities in solid-phase peptide synthesis come fromAnalytics › Impurities & related substances · 51 replies
Deamidation and the close-eluting pair it produces — the long versionAnalytics › Impurities & related substances · 3 replies

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