coming back to this is quantity testing available as a separate thing or bundled
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#test-results 2026-04-08
Wednesday41 messages8 participantstimes are UTC
Highlights from this day
- salt_bridge — coming back to this is quantity testing available as a separate thing or bundled 22:28
- nettle_notes — coming back to this quantity testing is usually a separate line item and it is the one worth paying for assay under label with good purity means you got less of the… 22:48
- hot_mailbox — quick one does a bad result on one lot condemn the whole supplier my read after three years of this: purity is mostly fine across the market and fill consistency is… 23:00
- hot_mailbox — certificate said 98.6 and the independent came back 99, is that a problem 23:10
- cross_border_cam — i told SWB about a result they would not have liked and they did not argue. credit where it is due 23:36
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
thats not great
ok so a point or two between the certificate and an independent result is inside what two labs disagree by
i had a result i am fairly sure was a handling error on my side and i logged it as such, anyway
i test roughly every tenth vial. it is a sampling strategy, not paranoia
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
do you test every order or sample it
log the lot number
does anyone log the negative results, the boring ones
coming back to this quantity testing is usually a separate line item and it is the one worth paying for
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
how many lots do you need before you can say anything about a supplier
underfill is more common than impurity. if you only test purity you are testing the less likely failure, from memory
has a supplier ever disputed a result posted here
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally, your mileage will differ
update from 15 months ago: retested the same supplier, result came back better, logged both
[edited]quick one does a bad result on one lot condemn the whole supplier
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
posting my PeptideMeter result on lot KP-0925, what do people make of it
how do you separate batch variance from supplier variance
thats a fill problem
attach the pdf
certificate said 98.6 and the independent came back 99, is that a problem
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a result without a lot number and a purchase date is an anecdote with a pdf attached
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind, n of 1 obviously
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
my vial assayed under label but the purity was fine, which matters more
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while im here assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem, ask me again in a month
anyone tested the same lot twice at different labs
thats within range
selection bias
do the results in this channel skew because people test when suspicious
i told SWB about a result they would not have liked and they did not argue. credit where it is due
anyone had a result they think was a lab error rather than a bad vial
log the boring results too. a channel that only records failures produces a false picture
*Medutest not the other one
weigh the vial before you reconstitute. it costs nothing and catches the common failure
if you are testing to settle an argument you will not settle it with n of 1
weigh it first
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