Topic summary

Preservatives: function, testing, and limits

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

This is a generated summary. It shows the 5 most-liked posts from a topic of 28, 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.

n.hartmannTL222 Jan 2025#4

Light sensitivity varies enormously between peptides depending on the residues present. Tryptophan-containing sequences are the ones where it matters most.

27 likes 18mo

l.wikstromTL29 Mar 2025#18

Aggregation is concentration-dependent, which is why reconstituting to a high concentration is not always the convenient choice it appears to be.

Marking that as an opinion rather than a finding.

21 likes 17mo

n.torrenceTL3Regular12 Mar 2025#19

Two things can be true about preservatives at once: the mechanism is plausible and the evidence for the size of the effect is thin. Most of the argument here is people defending the first against attacks on the second.

22 likes 17mo

h.hutchingsTL1Member17 Mar 2025#21

Quietly grateful for the plain phrasing. Not every thread gets that.

24 likes 16mo

IHollingworthTL2Member28 Mar 2025#25

Worth separating two things that post #23 runs together.

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.

Stating my assumptions rather than smuggling them in.

17 likes 16mo

Read the full topic (28 posts)

Suggested topics

Topic	Participants	Replies	Views	Activity
Buffers, pH and why a formulation is a formulation Pharmacology › Formulation chemistry counter-ion content cloudy or discoloured solution sterile water storage 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. A formulation question rather than a pharmacological one, though the two…	+11	15	51k	21mo
Coming back to: Solubility limits and what a cloudy solution is telling you Pharmacology › Formulation chemistry sterile water cloudy or discoloured solution storage counter-ion content On the subject in the title: Solubility limits and what a cloudy solution is telling you Working notes rather than a conclusion. Reading back through what has been written here about Solubility limits, three…	+38	43	29k	13h
Second pass at: Buffers, pH and why a formulation is a formulation Pharmacology › Formulation chemistry counter-ion content cloudy or discoloured solution sterile water Wiki Second pass at: 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 a small dataset on Buffers. It is mine, it is…	+24	28	1.5k	21mo
Coming back to: Adsorption to container surfaces and to plastics Pharmacology › Formulation chemistry bacteriostatic water counter-ion content storage sterile water Adsorption to container surfaces and to plastics — setting out what I have, and where I think it stops being reliable. Adsorption — I have the observation and I do not trust my interpretation of it, so I am…		2	459	17mo
Second pass at: Isotonicity and what happens when you get it wrong Pharmacology › Formulation chemistry counter-ion content storage bacteriostatic water sterile water Closed Second pass at: Isotonicity and what happens when you get it wrong — setting out what I have, and where I think it stops being reliable. Something about Isotonicity does not reconcile and I would like a…	+1	5	2.6k	11mo

Related topics — sharing the tags counter-ion content, storage, bacteriostatic water

Topic	Participants	Replies	Views	Activity
Coming back to: Pen dose counters: what a click does and does not guarantee Devices › Pens & autoinjectors storage subcutaneous injection dead volume Pen dose counters: what a click does and does not guarantee — setting out what I have, and where I think it stops being reliable. Reading back through what has been written here about Pen dose counters, three…		4	105	5mo
Charge states for a 4 kDa peptide, worked through Analytics › Mass spectrometry high-resolution MS counter-ion content charge states LC-MS Solved On the subject in the title: Charge states for a 4 kDa peptide, worked through Working notes rather than a conclusion. Working through the identity arithmetic and I would like it checked. retatrutide has a…	+124	146	15k	16mo
Swirling versus inverting versus leaving it alone Practice › Reconstitution concentration maths syringe units bacteriostatic water reconstitution On the subject in the title: Swirling versus inverting versus leaving it alone Working notes rather than a conclusion. Asking about swirling versus inverting versus leaving on behalf of the question I keep…		2	18k	18mo
A fridge failure and how I assessed the contents afterwards Devices › Cold chain cold chain storage temperature excursion A fridge failure and how I assessed the contents afterwards Writing it up because I had to work it out twice and would rather nobody else did. The question about fridge failure that I actually want answered…	+14	18	46k	17h
A vial that will not fully dissolve: what to check and in what order Practice › Reconstitution reconstitution bacteriostatic water syringe units Solved A vial that will not fully dissolve: what to check and in what order — setting out what I have, and where I think it stops being reliable. Practical question with the units stated, because I have seen how…	+12	16	40k	15mo