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u/tidy_vialdrawer_watch28

Came for one answer, stayed for three years.

member · joined 11 Dec 2023

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Overview — page 2 of 2

comment on the water content question that gets asked weekly, answered properly in c/coa · 328 points · 1 year ago

This. Area percent answers "what fraction of what the detector saw was the peak I wanted", and people read it as "how much peptide is in the vial".

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comment on the water content question that gets asked weekly, answered properly in c/coa · 125 points · 1 year ago

Correction: that is net peptide content, not purity. Different number, different meaning, and the document says so if you read the row label.

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comment on help me understand batch, I have read the wiki twice in c/coa · 205 points · 1 year ago

Batch number and date of analysis, are both on there?

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comment on [Discussion] ATTAIN is doing more work than we give it credit for in c/orforglipron · 68 points · 1 year ago

The analytical point, which this board keeps getting wrong by importing habits from the peptide side.

For a peptide, purity is typically reported as area percent by HPLC with identity by mass spectrometry, and the impurity classes are things like deletion and oxidation products. For a small molecule the relevant impurities are synthetic intermediates, degradants and residual solvents, and identity is established differently.

So the certificate you would want looks different, the questions to ask are different, and a "purity" figure quoted here is not comparable to one quoted on the peptide boards. Anybody posting a result should say what method produced it, which is good practice everywhere and essential here.

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comment on three years of water content threads, summarised so you do not have to read them in c/coa · 0 points · 1 year ago

Does the lot on the vial match the lot on the page?

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comment on help me understand area percent, I have read the wiki twice in c/coa · 31 points · 1 year ago

Batch number and date of analysis, are both on there?

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comment on [Discussion] lyophilised is doing more work than we give it credit for in c/coldchain · -32 points · 1 year ago

Moved everything off the fridge door after reading a thread here and my temperature log immediately got boring.

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comment on [Question] small molecule — what am I missing here in c/orforglipron · 1 points · 2 years ago

Cosigning on daily dosing. It changes the exposure profile and it changes adherence, in both directions.

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comment on [Question] small molecule — what am I missing here in c/orforglipron · 21 points · 2 years ago

Analytically this is a small-molecule identity and purity problem, not a peptide one. The methods, the impurity classes and the reference standards are all different.

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comment on does lyophilised actually matter or is it forum lore at this point in c/coldchain · 41 points · 2 years ago

the door shelf is the worst place in the fridge

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comment on [Discussion] can we stop arguing about ATTAIN until somebody posts a number in c/orforglipron · 1 points · 2 years ago

It is a non-peptide small-molecule agonist at the GLP-1 receptor. That is a substantial medicinal chemistry achievement: getting a small molecule to activate a receptor evolved for a peptide ligand.

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comment on [Vendor] TFC vs SSA on the same compound, same month — both cleared 98.0% in c/coa · 1k points · 2 years ago

Ask what the stability statement was written against — temperature, light, and whether it was the lyophilised powder or the reconstituted solution. Those are three different claims.

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comment on someone explain ice pack to me like I have not read a paper in years in c/coldchain · 2 points · 2 years ago

powder at room temperature for a few days is usually a non-event

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comment on someone explain ice pack to me like I have not read a paper in years in c/coldchain · 71 points · 2 years ago

A transit temperature logger records a distribution, and time above a threshold matters as much as peak temperature.

This is the distinction that resolves most threads here — powder and solution are different problems.

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comment on someone explain ice pack to me like I have not read a paper in years in c/coldchain · 141 points · 2 years ago

What actually matters, in order, because these threads always start at the wrong end.

State first: dry powder is comparatively robust, reconstituted solution is not. Most of the anxiety here is about powder and most of the real risk is about solution.

Then evidence: a warm gel pack is evidence about the pack. A logger is evidence about the box. Only a test is evidence about the material. People routinely reason from the first to the third and it does not follow.

Then prevention, which is dull and effective: shorter lanes where regional stock exists, rigid packaging, the middle of the fridge rather than the door, and the reconstitution date written on the glass.

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comment on [Discussion] can we stop arguing about batch until somebody posts a number in c/coa · 20 points · 2 years ago

Agreed, and the practical version is: ask for the itemised table.

laila_yilmaz has the distinction right — one is a fraction of the detector signal, the other is a fraction of the mass.

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comment on [PSA] excursion is not what most of this community thinks it is in c/coldchain · 1 points · 2 years ago

This. A liquid gel pack on arrival tells you about the pack’s duty cycle, not about the vial.

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comment on [Vendor] GL Biochem vs GGPeps on the same compound, same month — both cleared 97.5% in c/coa · 881 points · 2 years ago

Ask what the stability statement was written against — temperature, light, and whether it was the lyophilised powder or the reconstituted solution. Those are three different claims.

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comment on [Discussion] the area percent advice in here is 2 years out of date in c/coa · 117 points · 2 years ago

The PDF creation date being later than the analysis date is usually a re-issue or a re-export. It is worth one question and it is not evidence of anything on its own.

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