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c/coa·posted 7 months ago by u/janek_ferrari

[Meta] the certificate of analysis rule is doing its job and people should stop complaining

Lab Well Actually ×9 Slow Clap ×2 Long Haul ×1

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

The advice on related substances 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.

21,254 up / 15,759 down57% upvoted25 commentsid x7i1cp3 Dec 2025

25 comments

15 in this archive, depth 3

best — the order this archive was captured in

u/rohan_steiner602 points·7 months ago

the related substances line is where the story is

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u/janek_ferrariOP257 points·7 months ago

No. This is the kind of confident post that gets copied into a screenshot and repeated for years. Where is the evidence.

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u/amylin_amyamylin455 points·7 months ago·edited
i wish i had read this 16 months ago
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u/emeka_beaulieu278 points·7 months ago

purity and net content are two different numbers, same vial

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u/tidy_vialdrawer_pls306 points·7 months ago

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

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[deleted]217 points·7 months ago

[deleted]

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u/rohan_steiner86 points·7 months ago

You have restated the marketing copy. What is the actual substance here.

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u/janek_ferrariOP0 points·7 months ago

the method line is doing real work, not just window dressing

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u/tove_ogunleye215 points·7 months ago

PDF metadata is checkable in fifteen seconds

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u/purity_pedantanalytical63 points·7 months ago

PDF metadata is checkable in fifteen seconds

Disagree on that part. 97.9% and 97.6% on the same vial is normal.

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u/foam_head_fred30 points·7 months ago

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

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u/step_therapy_s105 points·7 months ago

redact your own name, not the vendor's batch details

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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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c/coa rules
  1. Post the full document. Cropped COAs that hide the batch number or date get removed.
  2. Redact your own name and order id, not the vendor's batch details.
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