mixed fonts and inconsistent kerning in one document is worth a second look
#coa-reading 2025-07-11
Friday35 messages8 participantstimes are UTC
Highlights from this day
- LC_MS_Lena — a certificate should name the method, the instrument, the column and the operator. most name none of those, someone check my working 18:29
- freeze_thaw — a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully 20:16
- luerlok — tfa or acetate, how do i tell from the paperwork 21:00
- luerlok — a vial can be 99.4% pure and hold 8.1mg of a 10mg label. both numbers are true and only one of them is the one you care about 21:15
does anyone keep a folder of certificates to compare over time
single wavelength detection can miss a co-eluting impurity that does not absorb there
a supplier certificate on its own is a starting point, not evidence. that is the whole reason the verification channel exists
*Medutest not the other one
Channel stats, last 30 days: 126 messages from 27 members.
a certificate should name the method, the instrument, the column and the operator. most name none of those, someone check my working
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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
nobody can authenticate a certificate from a scan. you authenticate the material by testing it yourself
why do some certificates report to one decimal and some to two
the retention time on this one is different from the last lot, problem
i have never seen a research certificate with an endotoxin result on it. not once
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
mixed fonts and inconsistent kerning in one document is worth a second look
retention time shifts between runs are normal. relative retention time is the number to compare
tfa counterion runs higher by mass than acetate. if the certificate does not say, you cannot do the mass balance
the font on this one changes halfway down, am i being paranoid
if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not
purity is what fraction of the contents is the target. assay is how many mg are actually there. different questions
i asked ERP for the method and they sent it. that alone put them ahead of most, not advice obviously
i was wrong about this for a year: area percent under-reports nothing, it just answers a different question than assay does
sorry to jump in i keep every certificate in a dated folder and compare them. two suppliers had not changed their template since 2019
purity is not assay
the paperwork can be perfect and the vial can still be light. weigh it
weigh the vial
one decimal versus two is usually just house style, not precision
a lab that reports "greater than 98%" rather than a number is telling you they did not integrate carefully
peak RRT area% note
1 0.42 0.31 solvent front
2 0.88 0.44 related substance
3 1.00 98.72 main
4 1.14 0.53 related substanceresidual solvents matter more than people think for anything that went through a lot of purification steps
seven_five_sweetthe honest summary is that a certificate tells you what the supplier says about a lot…
sterility and endotoxin are separate tests and almost nobody runs either on research material
water content is why an honest 10mg vial assays at 9.1. karl fischer titration, and most certificates omit it, your mileage will differ
check the lot
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Inter-lab diff for lot C-4402: 98.6% vs 99.4%. Within expected range.
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the related substances table is the interesting part. a row of "not detected" means they did not look hard
tfa or acetate, how do i tell from the paperwork
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two certificates from the same supplier have an identical chromatogram, is that normal
follow up whats the related substances table actually telling me
a vial can be 99.4% pure and hold 8.1mg of a 10mg label. both numbers are true and only one of them is the one you care about
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