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517
c/coa·posted 2 years ago by u/amylin_amy

tried purity for 3 weeks. here is what happened.

Explainer Slow Clap ×8

I have had 10 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 30 days on nominally the same lane, which matters more in summer than in February.

The independent number came back 97.9% against a claimed 98.0%, 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.

543 up / 26 down95% upvoted28 commentsid 1xrpuz28 Mar 2024

28 comments

20 in this archive, depth 5

best — the order this archive was captured in

u/coa_collectorMOD109 points·2 years ago

Retitled to remove editorialising. Put the evidence in the body.

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u/tuva_aalto36 points·2 years 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_amyOPamylin-15 points·2 years 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/cormac_pereira1 point·2 years ago

Slight fix: the number was 99.1, not 96.8. Decimal point, but a fairly consequential one.

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u/amylin_amyOPamylin1 point·2 years ago

Four months on the site and I was confusing area% and mass% in every post I made.

Disagree on that part. 98.4% and 98.3% on the same vial is normal.

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u/mikkel_correia49 points·2 years ago

axis labels included, always

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u/chidi_demir43 points·2 years ago

The COA I was holding said 96.8% area and I thought it was trash. Turns out the method was solid and the impurity profile was clean.

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u/tomas_lehtinen63 points·2 years ago

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

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u/gastric_emptying_g44 points·2 years ago

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

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u/neha_erdogan38 points·2 years ago

the batch number or it did not happen

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u/chidi_demir29 points·2 years ago

What were the related substances listed individually?

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[deleted]12 points·2 years ago

[deleted]

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u/katrin_girard9 points·2 years ago·edited

axis labels included, always

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u/ghrp_history28 points·2 years 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/aleksi_eriksen0 points·2 years ago

axis labels included, always

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u/first_hundred1 point·2 years ago

That is net peptide content, not purity. Different number, different meaning.

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u/yusuf_nakamura1 point·2 years ago

PDF metadata is checkable in fifteen seconds

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u/nikhil_lindqvist6 points·2 years 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_amyOPamylin2 points·2 years ago

the batch number or it did not happen

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u/dario_boateng22 points·2 years ago·edited

That is net peptide content, not purity. Different number, different meaning.

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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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