unrelated but how do you verify a certificate is actually from the lab it says
#coa-reading 2026-02-20
Friday40 messages9 participantstimes are UTC
Highlights from this day
- evidence_or_not — two certificates from the same supplier have an identical chromatogram, is that normal 08:40
- auckland_aliquot — i asked FGP for the method and they sent it. that alone put them ahead of most the paperwork can be perfect and the vial can still be light. weigh it 09:43
- LC_MS_Lena — does purity by hplc at one wavelength miss things 10:11
- VialBot — Testing queue: 2 submissions open, 38 awaiting dispatch. 11:05
- LC_MS_Lena — i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019 16:03
one decimal versus two is usually just house style, not precision
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two certificates from the same supplier have an identical chromatogram, is that normal
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a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
the three way match is vial, certificate, invoice. if all three agree you have something
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why would a vial be 99.2 pure and still assay under label
net peptide is gross mass minus water minus counterion. that is why 11.4mg of powder can be a correct 10mg vial
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update on the earlier thing the related substances table is the interesting part. a row of "not detected" means they did not look hard
the certificate from GL Biochem is the one i use to teach this because it actually has a populated impurity table
i asked FGP for the method and they sent it. that alone put them ahead of most
the paperwork can be perfect and the vial can still be light. weigh it
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does purity by hplc at one wavelength miss things
| Line | Claims | Does not claim |
|---|---|---|
| Purity (area %) | fraction of detected material that is the target | how many mg are in the vial |
| Assay / content | mg of target per vial | that it is sterile |
| Water content | mass fraction that is water | anything about purity |
| Counterion | salt form and its mass share | net peptide unless stated |
| Related substances | what else was seen | what was not looked for |
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
sterility and endotoxin are separate tests and almost nobody runs either on research material
the retention time on this one is different from the last lot, problem
the honest summary is that a certificate tells you what the supplier says about a lot they chose to test
i have never seen a research certificate with an endotoxin result on it. not once
mixed fonts and inconsistent kerning in one document is worth a second look
is water content normally on a certificate or do you have to ask
not evidence on its own
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same chromatogram
weigh the vial
residual solvents matter more than people think for anything that went through a lot of purification steps
the paperwork can be perfect and the vial can still be light. weigh it, i think
if you only read one line on a certificate, read the lot number. if you read two, read the assay
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does, i think
gross mass on a jewellery scale plus the water content is enough to catch most underfills
Testing queue: 2 submissions open, 38 awaiting dispatch.
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is endotoxin ever tested on research material
if you only read one line on a certificate, read the lot number. if you read two, read the assay
*PeptideMeter not the other one
right so the font on this one changes halfway down, am i being paranoid
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net not gross
whats the minimum a certificate has to have before you take it seriously
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself, someone check my working
evidence_or_notresidual solvents matter more than people think for anything that went through a lot…
update on the earlier thing purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
i have never seen a research certificate with an endotoxin result on it. not once
an identical chromatogram on two different lots is the single biggest tell there is
looks re-dated
no lot no certificate
i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
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water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it, someone check my working
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