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c/coa·submitted 6 days ago by u/quant_not_qual

net peptide content vs purity — two different numbers, same vial, and only one is on your COA

Discussionbranch of 6 comments

Following on from the area% thread, because the same confusion turns up in a second form. People read a 10mg vial at 99% purity and conclude they have 9.9mg of peptide. They do not. Purity is a ratio between chromatographic species; it says nothing about total mass. Net peptide content is a separate assay and it…

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6 comments, started 5 days ago
u/coa_collectorarchivist288 points·5 days ago

One in eight across my folder, and it clusters hard by vendor. WXT and BCH have it most of the time. Everyone else, rarely, and usually only when somebody asked.

Which tells you the assay is not hard or expensive — it tells you it is not demanded. If a hundred people asked for it on every order it would be on every document inside a year.

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u/quant_not_qualOP141 points·5 days ago

that is a much more actionable read than mine. it is a demand problem, not a capability problem.

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u/test_it_yourselfvetting118 points·5 days ago

then ask. every order. it costs one sentence in an email and the aggregate effect over a community this size is not nothing.

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u/karl_fischer_kev94 points·4 days ago

same argument for water content and it worked on at least one vendor already.

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u/ice_pack_auditcold chain72 points·4 days ago

and packaging. ERP went from foam and optimism to a proper cold box after about a year of members saying so in public.

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u/coa_collectorarchivist81 points·4 days ago

the collective-nagging mechanism is genuinely the most effective tool this community has and it never gets written up as one.

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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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