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

[Question] Australia — has anyone got a straight answer on purity

Question Clean Column ×3

I have had 18 orders now and I keep a table, so here is the honest summary rather than a vibe.

Material has been consistent. Communication has not. Shipping has varied by about 40 days on nominally the same lane, which matters more in summer than in February.

The independent number came back 96.8% against a claimed 97.2%, which I read as agreement rather than a discrepancy — inter-lab variance on this assay is a point or two either way and treating one lab as ground truth is how people end up in pointless arguments with vendors.

Batch number is in the comments. Ask if you want the method.

2,211 up / 2,300 down50% upvoted14 commentsid 1ynlke14 Oct 2024

14 comments

14 in this archive, depth 5

best — the order this archive was captured in

u/zeynep_zielinski11 points·1 year ago

What were the related substances listed individually?

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u/nadia_fonseca3 points·1 year ago

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

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u/step_therapy_s1 point·1 year ago

no "is this good?" without saying what the compound and claimed purity are

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u/tove_ogunleye1 point·1 year ago

area% is not mass%, and here is exactly why it matters

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u/emil_agyeman1 point·1 year ago

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

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u/yusuf_nakamura1 point·1 year ago

Not convinced. The evidence does not support that reading.

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u/aurel_boatengOP8 points·1 year 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/tidy_vialdrawer_watch282 points·1 year ago

PDF metadata is checkable in fifteen seconds

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u/purity_pedantanalytical5 points·1 year 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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[deleted]2 points·1 year ago

[deleted]

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u/fatima_wojcik-34 points·1 year ago

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

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u/valeria_girard1 point·1 year ago

post the whole document, not the headline number

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u/cesar_ivaturi1 point·1 year ago

the batch number or it did not happen

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u/alcohol_aversion1 point·1 year 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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