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c/coa·submitted 1 year ago by u/yusuf_nakamura

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

COAbranch of 8 comments

Something I keep coming back to: unpopular opinion: most of what gets said here about area percent is guesswork. Spent four months confusing area% and mass% in every post I made here. One explainer thread and it clicked permanently. Water content 3.8%, acetate 6.2%, purity 99%, net peptide about 90% of label weight.…

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8 comments, started 1 year ago
u/first_hundredMOD282 points·1 year ago

Left up and flaired Explainer. This is the answer we keep linking, written properly.

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[removed]210 points·1 year ago

[removed by moderator]

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u/gastric_emptying_g138 points·1 year ago

redact your own name, never the batch details

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u/zeynep_zielinski147 points·1 year ago

Asked TFC 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/clara_restrepo115 points·1 year ago

Cosigning. The batch identifier is load-bearing, and a certificate that cannot be tied to the vial in your hand is not about your vial.

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u/foam_head_fred136 points·1 year ago

chromatogram or it did not happen

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u/wrong_network_w46 points·1 year ago

My first certificate had a compound name, a percentage and a logo. I thought that was normal. It is not, and now I know what to ask for.

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u/bastian_moreau18 points·1 year ago

a total of 0.4% tells you less than four named impurities adding to 0.6%

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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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