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c/coa·submitted 2 years ago by u/marisol_frisk

[Vendor] SSA vs TFC on the same compound, same month — both cleared 97.5%

Explainerbranch of 7 comments

SSA vs TFC on the same compound, same month — both cleared 97.5%. I will put the method line and the batch identifier up front because that is what makes this checkable. 97.5%. Those are measured, not estimated, and not rounded up in my favour. Started keeping a folder of every certificate I have been sent. The ones…

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7 comments, started 2 years ago
u/aleksi_eriksen545 points·2 years ago

Agreed on asking for the storage condition. It is one line and it changes how you read the entire stability claim.

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u/tidy_vialdrawer_pls430 points·2 years ago

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

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u/andres_restrepo240 points·2 years ago

identity and quantity are two questions and most documents answer one

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u/blunt_coldbox2959 points·2 years ago

Small fix — 214nm, not 280nm. It matters here because the impurity you are asking about barely absorbs at the longer wavelength.

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u/marisol_friskOP44 points·2 years ago

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

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u/marisol_friskOP301 points·2 years ago

That is the catalogue certificate rather than the batch-specific one. Same layout, completely different status.

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u/ignacio_silva128 points·2 years ago·edited

Net peptide content is the fraction of the powder that is actually peptide once counterion, water and residual solvent are accounted for. A 99% pure acetate salt can still be about 85% peptide by mass.

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About c/coa

How to read a certificate of analysis and what it does and does not tell you. Area% versus mass%, identity versus quantity, water content, related substances, acetate counterions, and the difference between a vendor-supplied COA and an independent test on the vial you actually received.

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