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c/coa·posted 28 days ago by u/emeka_beaulieu

how do i tell an HPLC-UV COA from an LC-MS one at a glance

Suspicious Well Actually ×5

Confession thread, sort of.

I went from 1.0mg to 15mg much faster than I should have because the scale had stalled and I got impatient. The stall broke about 14 weeks later, at which point I had no way of knowing whether the dose increase did anything or whether it would have broken anyway.

So now I have sulphur burps I did not need and a data point I cannot interpret. Two lessons in one.

Posting it in the hope that somebody at week 12 reads it before doing the same thing.

830 up / 237 down78% upvoted6 commentsid 1yyclo1 Jul 2026

6 comments

5 in this archive, depth 4

best — the order this archive was captured in

u/certified_referenceMOD93 points·27 days ago

Flair changed to match the content. Read the sidebar before posting next time and we are square.

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u/sofia_ferreira78 points·27 days ago

Metadata check caught a COA that was created in a browser four months after the analysis date. Not evidence of fraud, but worth flagging to MKM.

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u/emeka_beaulieuOP45 points·27 days ago

The chromatogram trace is where the real information lives. The summary number is just a headline.

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u/certified_referenceQC11 points·27 days ago

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

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u/santiago_szabo-5 points·27 days ago

Rodent data is rodent data. Dose scaling is not linear and the models tell you what to investigate, not what to expect.

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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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