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c/coa·posted 6 months ago by u/dario_vermeulen

[Vendor] QST order #5 — Denmark, 15 days, no drama, receipts inside

Lab Cold Box ×4 Long Haul ×2

Right, the related substances question again, but with numbers this time.

I have 14 data points over 26 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 49, not week 3. People give up long before the interesting part.

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

2,635 up / 794 down77% upvoted17 commentsid 10jd9o2 Jan 2026

17 comments

5 in this archive, depth 2sorted by:

best — the order this archive was captured in

u/teodor_lokken104 points·6 months ago·edited

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

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[deleted]39 points·6 months ago

[deleted]

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u/emeka_chowdhury95 points·6 months ago

Tested the GLB raw material and a reseller vial side-by-side. Same purity claim, different impurity profiles. Handling matters.

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u/meera_sandvik69 points·6 months ago

Tested the GLB raw material and a reseller vial side-by-side.

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

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u/zaid_balogun72 points·6 months ago

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

Independent HPLC and mass spec. The number you get is the number they found.

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Custom peptides and amino acids direct from the manufacturer since 1998. ISO 9001 / cGMP. Batch COA every order.

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