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

what would you tell week-1 you about batch

COA Receipts ×2 Cold Box ×3

Right, the certificate of analysis question again, but with numbers this time.

I have 4 data points over 16 weeks. The pattern is consistent enough that I do not think it is chance, and boring enough that nobody is going to screenshot it, which is usually a good sign.

The thing I would flag for anyone new: the effect I am describing showed up at week 51, not week 5. People give up long before the interesting part.

Interested in whether this matches other people's logs or whether I am an outlier.

6,396 up / 4,659 down58% upvoted66 commentsid 1yog5h22 Jun 2026

66 comments

30 in this archive, depth 5

best — the order this archive was captured in

u/ignacio_silva185 points·1 months ago

Three years on this site and the questions have not changed at all. Which is depressing or reassuring depending on the day.

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u/anya_moreau66 points·1 months ago

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

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u/sofia_danquah75 points·1 months ago

purity and net content are two different numbers, same vial

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u/coa_janitormod · c/coa114 points·1 months ago

Disagree but this is the good kind of wrong — it is specific enough to be checked.

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u/cesar_ivaturi79 points·1 months ago

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

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u/andres_restrepo129 points·1 months ago

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

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u/amira_dumitru34 points·1 months ago

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

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u/first_hundredMOD75 points·1 months ago

Removed a chain here. The rule is one line long and it is not negotiable.

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u/teodor_lokken121 points·1 months ago

the batch number or it did not happen

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u/emeka_chowdhury80 points·1 months ago

Inter-lab variance on this kind of assay is routinely 1–2 points. Different column, different gradient, different integration.

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[removed]54 points·1 months ago

[removed by moderator]

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u/receptor_bias_rick78 points·1 months ago

PDF metadata is checkable in fifteen seconds

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u/noor_cardoso34 points·1 months ago·edited

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

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u/freya_baptista9 points·1 months ago

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

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u/anders_kuuselaOP0 points·1 months ago

Slight fix: the number was 99.3, not 93.7. Decimal point, but a fairly consequential one.

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u/hugo_bergstrom1 point·1 months ago

Slight fix: the number was 99.3, not 93.7.

Adding to this: water content is doing more work than the comment implies.

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u/anya_correia51 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/honest_syringe2442 points·1 months ago

What is the method line say? Not the technique, the actual method.

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u/teodor_jansen66 points·1 months ago

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

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u/wrong_network_w54 points·1 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/laila_yilmaz19 points·1 months ago

Cosigning. The batch number is load-bearing information.

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u/cato_achebe45 points·1 months ago

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

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u/receptor_bias_rick10 points·1 months ago

Strongly agree.

Yes, exactly this, and it is the bit that took me 78 weeks to accept.

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u/clara_danquah4 points·1 months ago

purity and net content are two different numbers, same vial

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u/coa_janitormod · c/coa36 points·1 months ago
oh thank god it is not just me
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u/anya_correia13 points·1 months ago

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

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u/alcohol_aversion17 points·1 months ago

What were the related substances listed individually?

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u/anders_kuuselaOP6 points·1 months ago

Four months on the site and I was confusing area% and mass% in every post I made. One explainer thread and it clicked.

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u/purity_pedantanalytical20 points·1 months ago

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

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u/nadia_kjaer14 points·1 months ago·edited

What is the method line say? Not the technique, the actual method.

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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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  1. Post the full document. Cropped COAs that hide the batch number or date get removed.
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