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c/coa·submitted 5 months ago by u/certified_reference

unpopular opinion: most of what gets said here about COA is guesswork

Suspiciousbranch of 6 comments

The title is the argument: unpopular opinion: most of what gets said here about COA is guesswork. Here is the rest of it. 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. Ask what the stability…

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6 comments, started 5 months ago
u/first_hundredMOD567 points·5 months ago

Your name and address edited out of the screenshot above. The batch details are untouched and should stay.

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u/cormac_pereira223 points·5 months ago

Careful — "the metadata looks odd" is a reason to ask a question, not a conclusion. Re-issues are ordinary.

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u/aurel_boateng284 points·5 months ago

Careful — "the metadata looks odd" is a reason to ask a question, not a conclusion.

Agreed, and the practical version is: ask for the itemised table. If it exists, you get it.

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u/nabila_espinoza281 points·5 months ago

batch number, date of analysis, method, individual impurities — that is the minimum set

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u/tuva_aalto128 points·5 months ago

the counterion is part of the mass you paid for

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u/blunt_coldbox29103 points·5 months 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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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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