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

switched from 12.5mg to 0.5mg and the injection-site soreness got better, not worse

Explainer Long Haul ×7 Slow Clap ×2 Cold Box ×3

Trying to settle this properly because the thread from last year went in circles.

The claim: COA matters. The counter-claim: it is measurement error. Both sides have been asserting it confidently for about 7 months without either producing anything.

What would actually settle it is 39 people measuring the same thing the same way. I have started; my numbers are below. They lean one way but not strongly enough for me to declare victory.

If you have data, post the data. If you have an opinion, flair it as an opinion.

9,173 up / 1,734 down84% upvoted36 commentsid 1wxu7e30 Jul 2024

36 comments

25 in this archive, depth 4

best — the order this archive was captured in

u/sofia_danquah796 points·1 year ago·edited

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

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u/rania_okonkwoOP537 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/rania_okonkwoOP350 points·1 year ago·edited

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

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[deleted]130 points·1 year ago

[deleted]

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u/yara_antonsen127 points·1 year ago

the batch number or it did not happen

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u/karma_irrelevant440 points·1 year ago

Did they give you the chromatogram or just the summary line?

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u/blunt_coldbox29275 points·1 year ago

Did they give you the chromatogram or just the summary line?

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

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u/purity_pedantanalytical142 points·1 year ago

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

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u/wrong_network_w-10 points·1 year 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/cormac_pereira239 points·1 year ago

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

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u/coa_janitormod · c/coa186 points·1 year ago·edited

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

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u/katrin_girard45 points·1 year ago

This is the correct framing.

Yes, exactly this, and it is the bit that took me 47 weeks to accept.

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u/clara_restrepo13 points·1 year ago

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

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u/amylin_amyamylin167 points·1 year ago

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

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u/gallbladder_gary0 points·1 year ago

Water content matters more than people think. If a vial is carrying residual moisture, your "10mg" is not 10mg of peptide.

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u/india_generic_g1 point·1 year ago

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

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u/nikhil_lindqvist165 points·1 year ago

Dead space in the needle hub holds a small but non-trivial volume. On low-volume draws that can be several units.

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u/laila_wojcik85 points·1 year 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/rania_okonkwoOP63 points·1 year ago

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

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u/ghrp_history46 points·1 year ago

post the whole document, not the headline number

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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
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