On post #29 — agreed on the reasoning, with one qualification.
My position on Adsorptive losses is current rather than settled. I have revised it once already and I expect to again, so treat it accordingly.
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Practice · Storage & stability · continued
Second pass at: Adsorptive losses at low concentration, and why dilute solutions are fragile posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
chromatogram, post #23: I want to gently push back on the reply above about storage extrapolation. The advice is sound and the confidence is not. We are extrapolating from stability data on a licensed formulation to a preparation that differs in concentration, diluent and container. That extrapolation is reasonable and it is still an extrapolation. Saying so… Go to post
Worth stating the null on Adsorptive losses before we explain it: the observation may be nothing. That possibility deserves a sentence and usually does not get one.
Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear.
I am confident about the direction and much less about the magnitude.
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Post #33 describes the usual case. This is about the unusual one.
Refrigeration slows degradation. Repeated warming and cooling is worse than continuous refrigeration. Light exposure is worth avoiding. The concentration matters because adsorptive losses are proportionally larger in dilute solutions. All of that is reasonably well supported.
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Collapsed as off-topic by two members at trust level 3 or above
Adding the measurement that post #33 says would settle it.
Temperature excursions: if a vial sat at room temperature for a time, the question is whether the excursion was long enough to cause damage. Hours at room temperature is usually low risk. Days to weeks raises the risk. If you are unsure, contacting the supplier is more informative than guessing.
Knowlton, post #14: Post #11 is the version of this I will quote in future. One addition. One caution on Adsorptive losses: everything above assumes the underlying documentation is what it claims to be. That assumption is doing real work and is rarely stated. Go to post
A note on how Adsorptive losses gets discussed rather than on Adsorptive losses itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.
Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed.
That is all I can say without guessing.
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c.amankwah, post #28: Careful with the language on Adsorptive losses. "Not detected" and "not present" are different findings and the first is a statement about the method. Go to post
Something worth flagging about Adsorptive losses: the strongest-sounding claims in this thread are the ones with no source attached, which is the usual pattern and not a coincidence.
Reading rather than contributing, but this is the most useful thread I have found on it.
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This follows post #38 rather than contradicting it.
Where I have landed on Adsorptive losses, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it.
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Worth separating two things that post #41 runs together.
Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear.
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p.silva, post #16: Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed. For what it is worth, the same held on the two occasions I checked. Go to post
Small correction to my own earlier position on Adsorptive losses. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.
r.ekstrom, post #26: Freeze-thaw: some peptide solutions tolerate freezing poorly because ice crystals damage protein structure. Whether your specific solution tolerates it depends on the formulation and is not something to test empirically. The conservative position is not to freeze. Worth checking against a second source before it gets quoted onward. Go to post
Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed.
I am aware this is the third time this month I have made this point.
On Adsorptive losses: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.
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I want to gently push back on the reply above about storage extrapolation. The advice is sound and the confidence is not.
We are extrapolating from stability data on a licensed formulation to a preparation that differs in concentration, diluent and container. That extrapolation is reasonable and it is still an extrapolation. Saying so does not weaken the practical recommendation; it just stops the recommendation from hardening into a fact that someone cites as certain.
Happy to be the one who is wrong here if it settles the question.
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r.venkatesan, post #33: Clarity is a weak test. A solution can lose a significant fraction of its active content to degradation or adsorption while remaining perfectly clear. I am confident about the direction and much less about the magnitude. Go to post
No notes. Posting so the count is not one.
Published stability data applies specifically to the formulation studied, under the specific conditions stated. It does not automatically transfer to something reconstituted at home in a different concentration with a different diluent. That caveat is not small.
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v.malinowski, post #6: I had written a reply contradicting post #4 and deleted it. Here is what survived. On Adsorptive losses I would separate what is worth knowing from what is worth acting on. The first list is long and the second is short, and conflating them is how threads get heated. Go to post
Building on post #50 rather than restating it.
Small methodological point on Adsorptive losses: repeating a measurement is cheap and resolves most of what is being argued about here at no cost to anyone.
a.jansen, post #41: This follows post #38 rather than contradicting it. Where I have landed on Adsorptive losses, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it. Go to post
Visible particulate is a strong signal in the other direction: it is a reason to stop and ask rather than to filter and proceed.
I would be interested in a counterexample if anyone has one.
Trying to state the Adsorptive losses position in a way that someone who disagrees would recognise as fair, because I do not think the version in this thread passes that test.
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s.rasmussen, post #1: On the subject in the title: Second pass at: Adsorptive losses at low concentration, and why dilute solutions are fragile Working notes rather than a conclusion. The question about Adsorptive losses that I actually want answered is the second one below. The first is context and I have kept it short. Both are stated with units, and I… Go to post
Post #55 is the version of this I will quote in future. One addition.
Protecting from light: amber vials or opaque containers reduce light exposure. If you are storing for long periods and light matters, this is worth doing. For short-term prepared solutions, ordinary storage away from direct sunlight is usually adequate.
Having read the whole Adsorptive losses thread before replying: the question in the first post has not actually been answered yet, and three of us have answered a nearby one instead.
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Following this. I have the same question and no better information than the first post.
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