log the boring ones
#test-results 2025-05-21
Wednesday40 messages10 participantstimes are UTC
Highlights from this day
- LC_MS_Lena — certificate said 97.4 and the independent came back 96.8, is that a problem 09:34
- monoisotopic — my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ 10:06
- salt_bridge — i have never regretted spending the money on a test. i have regretted not testing twice 10:07
- pbs_pip — whats the underfill rate people are actually seeing 10:48
- HPLC_Hank — assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem 11:40
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
when did you buy it
[edited]is anyone tracking results over time in a way they would share
follow up does a bad result on one lot condemn the whole supplier
certificate said 97.4 and the independent came back 96.8, is that a problem
🎉4💀5
nice result
👀5
anyone tested the same lot twice at different labs
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
lot bought purity assay/label
A-2418 2025-03 99.1% 9.6 / 10mg
A-2601 2025-08 98.7% 9.8 / 10mg
B-0114 2026-01 99.3% 9.4 / 10mg
B-0329 2026-04 98.9% 9.9 / 10mgi have never regretted spending the money on a test. i have regretted not testing twice
✅16⚠️7🔥2
if the vial has been through a bad transit you are testing the transit as much as the supplier
whats the underfill rate people are actually seeing
📈13❤️13🙏8
97.4 against a certificate of 99 is fine. the same supplier landing low four times in a row is a question
thats within range
test it again
✅9
is a purity-only test worth the money if underfill is the common failure
*VendorInvestigate not the other one
one data point
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
🎉6👍1👀6
whats the lot
follow up i had a result i am fairly sure was a handling error on my side and i logged it as such
log the lot number
follow up my sheet has 8 lots from SGN with a spread under a point, which is tight, thats one data point
a single sample tells you about a single vial. that is genuinely all it tells you
log the boring results too. a channel that only records failures produces a false picture
does anyone log the negative results, the boring ones
i told GL Biochem about a result they would not have liked and they did not argue. credit where it is due
do you test every order or sample it
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
slightly off topic but how do you separate batch variance from supplier variance
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
anyone had a result they think was a lab error rather than a bad vial
🤝5🧪1
is it worth testing if the vial has already been through a warm transit
how do you post a result so it is actually useful to somebody in a year
a supplier disputing a result is rare here and it has never gone well for the supplier
quantity testing is usually a separate line item and it is the one worth paying for
selection bias
a point or two between the certificate and an independent result is inside what two labs disagree by