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

[Discussion] the related substances advice in here is 3 years out of date

Discussionbranch of 7 comments

the related substances advice in here is 3 years out of date. It is the sort of thing everyone half-believes and nobody writes down. 3 years — those are the numbers, and they are the ones I am willing to defend. Related substances itemised individually is a much stronger document than a single total, because it tells…

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7 comments, started 2 years ago
u/karma_irrelevant372 points·2 years ago

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

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u/certified_referenceQC141 points·2 years ago

post the whole document, not the headline number

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u/amira_dumitru118 points·2 years ago

Asked QSC for the batch-specific certificate and had the full document — batch, date, method line naming the column — inside six hours. That is now my baseline for everybody.

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u/janek_ferrari132 points·2 years ago

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

Disagree on this specific point. Two honest labs can resolve that impurity differently and report different numbers.

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u/freya_baptista84 points·2 years ago

Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.

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u/coa_janitormod · c/coa0 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/coa_collectorarchivist157 points·2 years ago

Yes. The structure of the document matters at least as much as the number printed on it.

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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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