Topic summary

Residual solvents and scavengers: what is looked for — what changed since

Analytics › Impurities & related substances forced degradation water content data table HPLC counter-ion content Solved

This is a generated summary. It shows the 6 most-liked posts from a topic of 42, 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.

OkaforTL3Regular23 Jan 2026#2

This follows the opening post rather than contradicting it.

Incomplete deprotection: mass higher by the protecting group mass. Usually markedly later eluting. A synthesis artifact from incomplete removal of protecting groups.

24 likes 6mo

sterile_fileTL3Regular Solution9 Feb 2026#6

Picking up post #3: that is the part I would want checked first.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

32 likes 6mo

ma.balogunTL2 Moderator20 Feb 2026#9

a.stephanopoulos, post #4: Oxidation at methionine and tryptophan: adds 16 per oxygen. Usually elutes earlier. Oxidation is common in storage, especially if the solution is exposed to light or if antioxidants are not present. Go to post

I read post #7 twice before replying, because I had assumed the opposite.

Dimer and higher-order multimers: two or more peptide molecules bonded together. They appear at double the mass and higher. They may or may not separate from the monomer on HPLC depending on the method.

25 likes in reply to #4 5mo

h.brandtTL2 Moderator2 Mar 2026#12

I read post #10 twice before replying, because I had assumed the opposite.

Off-target structures: if the sequence synthesis goes wrong, a completely different amino acid can be incorporated. The resulting off-target peptide is a structural isomer with the same mass but a different sequence. No chromatographic purity method detects this without a reference standard.

25 likes 5mo

glossary_checkTL2Member16 Apr 2026#28

post #27 answers the question as asked. The question underneath it is different.

27 likes 3mo

DSakamotoTL3Regular28 Apr 2026#33

Picking up post #30: that is the part I would want checked first.

Residual solvents: traces of solvents used in purification. These are usually tested by gas chromatography, not by HPLC. A specification for residual solvents should be stated separately from the purity.

33 likes 3mo

Read the full topic (42 posts)

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