an identical chromatogram on two different lots is the single biggest tell there is
#coa-reading 2025-03-03
Monday39 messages7 participantstimes are UTC
Highlights from this day
- tarpit_tam — a COA is a record that a named lab ran named methods on a named lot and got these numbers. that is all it is. it is not a guarantee about your vial, it is a report… 14:37
- verify_or_dont — the GL Biochem sheets i get from a reseller are interesting because the header is a real GL Biochem template but the tested product line has been retyped in a… 17:23
- bea_reconstitutes — a few people have emailed QA departments with a lot number and got a yes or no. success rate is maybe one in five and it depends entirely on whether they think you… 17:32
- chlorhex — nobody here is telling you what to put in your body, just how to read a piece of paper. keep it that way 17:48
not evidence on its own
single wavelength detection can miss a co-eluting impurity that does not absorb there
gross mass on a jewellery scale plus the water content is enough to catch most underfills
why do some certificates report to one decimal and some to two
i asked TFC for the method and they sent it. that alone put them ahead of most
test it yourself
good certificate actually
14:29week_zero joined
my order came with a COA and i can just about read the header. it says 99.2% is that good
good for what
purity?
99.2% of the peak area that made it past the detector at 214nm. thats the entire claim on that line
a COA is a record that a named lab ran named methods on a named lot and got these numbers.
that is all it is.
it is not a guarantee about your vial, it is a report about a sample of a lot.
if any of those three names is missing the document is decoration
which names
lab, method, lot
and a date. undated COAs float around for years
the WuXi TIDES paperwork i have has all four plus the analyst initials, which is more than most
wuxitides-COA-WXT-24-0713.pdf
3 pages · 412 KB · not retained in the public archive
so what do i actually look at
in order of how much it changes your decision:
so, field by field
| Field | What it tells you | If it is missing |
|---|---|---|
| Lot / batch no. | which physical run this describes | the document describes nothing |
| Test date | how old the data is vs your vial | could be a 2022 lot |
| Purity by HPLC (area%) | relative size of the main peak | no purity claim at all |
| Assay / content (mg per vial) | how much peptide is actually there | you know nothing about dose |
| Water content (KF) | how much of the mass is water | assay is unanchored |
| Counterion / net peptide | gross mass vs net peptide | mg figure is inflated |
| Related substances table | what the impurities are | the 0.8% is a black box |
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mine has three of those
which three
lot, date, purity
so you know the main peak was big. you do not know how much peptide is in the vial
isnt that the same thing
no, and that is the single most misunderstood line on any COA. hold on, that deserves its own go
there is a whole conversation on it further down this channel, worth reading before you buy again
the GL Biochem sheets i get from a reseller are interesting because the header is a real GL Biochem template but the tested product line has been retyped in a different font
thats a flag on its own
not necessarily fake, could be a reseller filling in their own SKU. but it means nobody signed for that line
correct. a COA is a chain of accountability. every retyped field breaks a link in it
does anyone actually verify these with the manufacturer
a few people have emailed QA departments with a lot number and got a yes or no. success rate is maybe one in five and it depends entirely on whether they think you are a customer
glbiochem.net has a contact form, i got a polite nothing
which is the honest outcome. absence of confirmation is not proof of forgery
ok this is more depressing than i expected
welcome to #coa-reading
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nobody here is telling you what to put in your body, just how to read a piece of paper. keep it that way
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