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c/coa·posted 17 days ago by u/teodor_lokken

[Explainer] the four things a COA must have or it is decorative

Explainer Receipts ×3 Sourced ×1

purity. That is the whole post, but I will justify it.

Everything else people worry about in c/sideeffects is downstream of it. Titration speed, muscle cramps, the endless dose arguments — most of it resolves if you sort purity out first, and almost nobody does.

I say this having got it wrong for 12 months. My triglycerides was the thing that eventually made me pay attention, which is a stupid way to learn a lesson that was in the sidebar the whole time.

1,898 up / 244 down89% upvoted32 commentsid 1vwgz213 Jul 2026

32 comments

19 in this archive, depth 5

best — the order this archive was captured in

u/honest_syringe24257 points·16 days 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/bastian_aalto177 points·15 days ago

axis labels included, always

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u/soren_nkemelu71 points·15 days ago

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

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u/teodor_lokkenOP127 points·15 days ago

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

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u/bastian_moreau0 points·15 days ago

Respectfully this is a sample of one presented as a finding.

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u/wanjiru_varga0 points·14 days ago·edited

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

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u/blunt_coldbox291 point·14 days ago

PDF metadata is checkable in fifteen seconds

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u/rohan_steiner106 points·14 days ago

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

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

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u/milos_vanhecke40 points·15 days ago

Slight fix: the number was 95.1, not 94.2. Decimal point, but a fairly consequential one.

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u/teodor_lokkenOP22 points·14 days ago

Slight fix: the number was 95.1, not 94.2.

Disagree on that part. 98.1% and 98.3% on the same vial is normal.

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u/anders_kuusela-37 points·17 days 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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u/emeka_chowdhury1 point·16 days ago

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

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u/teodor_lokkenOP1 point·16 days ago

Asked TFC for the batch-specific COA and they sent it within six hours, full document, batch number, date, everything. That is the baseline.

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u/sig_figs_sammod · analytical1 point·17 days ago

Cosigning. The batch number is load-bearing information.

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u/camila_lindqvist57 points·16 days 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/first_hundred47 points·15 days ago·edited

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

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u/anecdata_annie17 points·15 days 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/step_therapy_s20 points·15 days ago

the batch number or it did not happen

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u/first_hundred10 points·15 days ago

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

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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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