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c/coa·posted 2 years ago by u/sig_figs_sam

area percent — 12 things I got wrong before I got it right

COA Clean Column ×5 The Quiet One ×1

Something I noticed reading old threads that I have not seen said out loud.

The advice on COA in this community changed substantially around the start of last year, and nobody went back and updated the older posts. So depending on which thread the search engine hands you, you get two contradictory answers with the same confidence.

I have listed what I think the current consensus is below. Correct me — that is the point of posting it.

3,099 up / 625 down83% upvoted13 commentsid 4jthd17 Jan 2024

13 comments

3 in this archive, depth 1

best — the order this archive was captured in

u/camila_lindqvist221 points·2 years ago

purity and net content are two different numbers, same vial

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u/anders_kuusela187 points·2 years ago

area% is not mass%, and here is exactly why it matters

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u/blunt_coldbox2994 points·2 years ago

PDF metadata is checkable in fifteen seconds

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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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Independent HPLC and mass spec. The number you get is the number they found.

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