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c/coa·posted 1 months ago by u/coa_janitor

the water content question that gets asked weekly, answered properly

Lab Cold Box ×2 Slow Clap ×3 Well Actually ×3

Quick one. Canada here.

related substances works very differently where I live than in the threads that dominate the front page, and I keep seeing people confidently given advice that simply does not apply outside the US.

Specifics: the route I used took 20 weeks and cost roughly what I expected. The admin was worse than the cost. The thing that would have saved me the most time was knowing which document to ask for at the start.

Happy to answer questions from anyone in the same jurisdiction.

12,671 up / 9,321 down58% upvoted28 commentsid 7bawn2 Jun 2026

28 comments

20 in this archive, depth 6

best — the order this archive was captured in

u/teodor_jansen292 points·1 months ago·edited

Mechanistically the bit that matters is certificate of analysis. It explains most of the early profile and a decent chunk of the outcome.

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[removed]114 points·1 months ago

[removed by moderator]

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u/foam_head_fred55 points·1 months ago

axis labels included, always

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u/certified_referenceMOD290 points·1 months ago

Retitled to remove editorialising. Put the evidence in the body.

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u/janek_ferrari118 points·1 months ago

chromatogram or it did not happen

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u/liv_nkemelu228 points·1 months ago·edited

Yeah, 96.8% area is not the problem, the missing impurity breakdown is the problem.

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u/joaquin_ivaturi140 points·1 months ago

The confident tone is doing a lot of work that the evidence is not.

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u/rohan_steiner129 points·1 months ago

Retitled to remove editorialising.

Yes, exactly this, and it is the bit that took me 25 weeks to accept.

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u/ismael_eriksen69 points·1 months ago

chromatogram or it did not happen

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u/ghrp_history34 points·1 months ago

Yeah, 96.8% area is not the problem, the missing impurity breakdown is the problem.

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u/sunday_shot_sal18 points·1 months ago

I am going to push back on this slightly.

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u/coa_janitorOPmod · c/coa13 points·1 months ago

Water content was 3.8%, acetate was 6.2%, purity was 99%, but net peptide was only 90% of the label weight. Perfectly honest, just chemistry.

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u/yusuf_nakamura220 points·1 months ago

Strongly agree. Mass% and area% are answering different questions on the same document.

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u/isabela_nilsen259 points·1 months ago

Small correction: the trial was 9 weeks, not 15. Does not change your point but people will quote it.

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u/tidy_vialdrawer_pls153 points·1 months ago

Every time this gets posted it hits the front page and every time someone has to re-explain it.

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u/coa_janitorOPmod · c/coa0 points·1 months ago

This is the correct framing. The COA structure matters as much as the number.

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u/foam_head_fred95 points·1 months ago
i have this exact spreadsheet
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u/priya_palacios56 points·1 months ago

post the whole document, not the headline number

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u/coa_janitorOPmod · c/coa43 points·1 months ago

Edit to your parent would help — the concentration you quoted assumes one scenario and you have written another above it.

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u/freya_baptista14 points·1 months ago

Slight fix: the number was 97.2, not 97.4. Decimal point, but a fairly consequential one.

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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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