thats a fill problem
#test-results 2026-05-04
Monday48 messages11 participantstimes are UTC
Highlights from this day
- HPLC_Hank — i have never regretted spending the money on a test. i have regretted not testing twice 19:02
- ms_ms_mira — if you are testing to settle an argument you will not settle it with n of 1 21:48
- HPLC_Hank — i told FGP about a result they would not have liked and they did not argue. credit where it is due 22:39
a single sample tells you about a single vial. that is genuinely all it tells you
test it again
i have never regretted spending the money on a test. i have regretted not testing twice
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 / 10mg🤝1👍12
update on the earlier thing assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
*VendorInvestigate not the other one
ok so my sheet has 6 lots from ERP with a spread under a point, which is tight
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
does anyone log the negative results, the boring ones
a result without a lot number and a purchase date is an anecdote with a pdf attached
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when did you buy it
follow up quantity testing is usually a separate line item and it is the one worth paying for
while im here a point or two between the certificate and an independent result is inside what two labs disagree by
whats the lot
i had a result i am fairly sure was a handling error on my side and i logged it as such
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm, take that with a pinch of salt
log the boring results too. a channel that only records failures produces a false picture, anyway
update from 1 months ago: retested the same supplier, result came back better, logged both
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thats within range
if the vial has been through a bad transit you are testing the transit as much as the supplier
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my vial assayed under label but the purity was fine, which matters more
weigh the vial before you reconstitute. it costs nothing and catches the common failure
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
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a supplier disputing a result is rare here and it has never gone well for the supplier
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one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
thats not great
selection bias
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
weigh it first
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
does a bad result on one lot condemn the whole supplier
which lab
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underfill is more common than impurity. if you only test purity you are testing the less likely failure
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nice result
posting my PeptideMeter result on lot B-0114, what do people make of it
97.4 against a certificate of 98.1 is fine. the same supplier landing low four times in a row is a question
[edited]one data point
i told MKM about a result they would not have liked and they did not argue. credit where it is due
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the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
if you are testing to settle an argument you will not settle it with n of 1
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log the lot number
my sheet has 4 lots from SSA with a spread under a point, which is tight
coming back after 24 months with a follow up result, where do i put it
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log the boring ones
ok so i test roughly every tenth vial. it is a sampling strategy, not paranoia
i told FGP about a result they would not have liked and they did not argue. credit where it is due
🤝12
attach the pdf
how do you post a result so it is actually useful to somebody in a year
update from 17 months ago: retested the same supplier, result came back better, logged both