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c/coa·posted 1 year ago by u/clara_danquah

certificate of analysis: the version I wish someone had shown me in week 1

Lab Clean Column ×4 Sourced ×3 Receipts ×2

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

I have 20 data points over 32 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 55, not week 9. People give up long before the interesting part.

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

7,091 up / 1,493 down83% upvoted41 commentsid 24dxnx30 Jan 2025

41 comments

19 in this archive, depth 5

best — the order this archive was captured in

u/anders_kuusela-14 points·1 year ago

The evidence standard in c/vendorvetting gets called too strict about once a month, and every time, the thread ends with the complainant agreeing.

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[removed]1 point·1 year ago

[removed by moderator]

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u/dario_vermeulen1 point·1 year ago

purity and net content are two different numbers, same vial

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u/clara_danquahOP1 point·1 year ago

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

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u/stablecoin_steve1 point·1 year ago

axis labels included, always

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u/rania_okonkwo1 point·1 year ago

purity and net content are two different numbers, same vial

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u/rohan_steiner1 point·1 year ago·edited

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

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u/clara_danquahOP1 point·1 year ago

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

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u/valeria_karlsen1 point·1 year ago·edited

the batch number or it did not happen

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u/wrong_network_w366 points·1 year ago

post the whole document, not the headline number

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u/nabila_espinoza131 points·1 year ago

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

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u/sofia_danquah94 points·1 year ago

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

Yes, exactly this, and it is the bit that took me 49 weeks to accept.

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u/andres_restrepo43 points·1 year ago

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

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u/clara_danquahOP66 points·1 year ago

the batch number or it did not happen

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u/purity_pedantMOD265 points·1 year ago

Tracking number removed. It identifies both ends of a shipment.

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u/katrin_girard159 points·1 year ago

Water content on the document? That affects your concentration math.

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u/clara_restrepo121 points·1 year ago

Are you looking at area% or net peptide content? Different numbers.

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u/nadia_fonseca127 points·1 year ago

Titration speed is a side-effect dial far more than an efficacy dial.

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u/honest_syringe24100 points·1 year ago·edited

Slight fix: the number was 98.0, not 98.1. 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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c/coa rules
  1. Post the full document. Cropped COAs that hide the batch number or date get removed.
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