Topic summary

Adsorption to container surfaces and to plastics

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

This is a generated summary. It shows the 5 most-liked posts from a topic of 18, 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.

c.tullochTL226 Dec 2025#1

On the subject in the title: Adsorption to container surfaces and to plastics Working notes rather than a conclusion.

I was wrong about adsorption in a thread last spring and I would like to correct it publicly rather than quietly.

The error was in the units, which changed the conclusion by an order of magnitude. Setting out the corrected version, and the way I now check for that class of mistake.

37 likes 7mo

m.lehtinenTL221 Jan 2026#9

a.westergaard, post #7: Reading back through the adsorption threads from last year, the same three questions come up every time and only one of them has ever been answered properly. That seems like a documentation gap rather than a knowledge gap. Go to post

I have no financial interest in anything named in this thread and I want to say so before I comment on adsorption, because it is the sort of subject where it matters.

9 likes in reply to #7 6mo

c.cardosoTL224 Jan 2026#10

On post #8 — agreed on the reasoning, with one qualification.

Practical answer on adsorption, since the theoretical one is upthread: do the simplest check first, write down the result, and only then decide whether the complicated explanation is needed. It usually is not.

21 likes 6mo

peak_purityTL3Analytical chemist31 Jan 2026#13

Surfactants such as polysorbate are added to prevent adsorption and aggregation at interfaces. In a bare research preparation there is nothing performing that function.

20 likes 6mo

m.dalgaardTL3Regular9 Feb 2026#17

I read post #16 twice before replying, because I had assumed the opposite.

Counter-ion exchange from trifluoroacetate to acetate is a purification step with a cost, and material sold without it retains TFA. That affects mass balance and can affect biological assays.

14 likes 6mo

Read the full topic (18 posts)

This topic was referenced in

About the Formulation chemistry categoryPharmacology › Formulation chemistry · 4 replies
Buffers, pH and why a formulation is a formulationPharmacology › Formulation chemistry · 15 replies
[2026 update] Buffers, pH and why a formulation is a formulationPharmacology › Formulation chemistry · 2 replies

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