Topic summary

Buffers, pH and why a formulation is a formulation

Pharmacology › Formulation chemistry counter-ion content cloudy or discoloured solution sterile water storage

This is a generated summary. It shows the 5 most-liked posts from a topic of 16, 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.

lc_gradientTL3Analytical chemist25 Oct 2024 · edited#3

Buchholz, post #1: Buffers, pH and why a formulation is a formulation Writing it up because I had to work it out twice and would rather nobody else did. Posting the method first, because I know what the first three replies will otherwise be. Column: C18, 4.6 x 250 mm, 5 um Mobile phase: 0.1% TFA in water / 0.1% TFA in acetonitrile Gradient: 6% to 69%… Go to post

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

Amino acid residues and formulation: the specific sequence and composition of a peptide affects what formulation conditions it tolerates. Sequences high in methionine need more antioxidant protection. Sequences prone to aggregation need different pH or additive protection.

24 likes in reply to #1 21mo

s.okaforTL2 Moderator26 Oct 2024#4

Antioxidants: compounds that prevent oxidation (which damages peptides) are sometimes included. Methionine oxidation is a common degradation pathway and antioxidants help prevent it.

11 likes 21mo

r.erdoganTL2 Moderator27 Oct 2024#6

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.

17 likes 21mo

titration_diaryTL3Regular28 Oct 2024#9

Worth separating two things that post #5 runs together.

Fill volume and headspace: the amount of solution in a vial and the air above it affect how much the solution is exposed to oxygen during storage. Less headspace means less oxygen exposure.

10 likes 21mo

k.redgraveTL2Member30 Oct 2024#13

Picking up post #10: that is the part I would want checked first.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

25 likes 21mo

Read the full topic (16 posts)

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