i test roughly every tenth vial. it is a sampling strategy, not paranoia, ask me again in a month
#test-results 2025-10-04
Saturday44 messages9 participantstimes are UTC
Highlights from this day
- LC_MS_Lena — 98.6 against a certificate of 97.4 is fine. the same supplier landing low four times in a row is a question, n of 1 obviously 20:52
- two_three_lifts — my result contradicts the supplier certificate, do i tell them 21:27
- noct.titrate — how do you post a result so it is actually useful to somebody in a year 21:32
- ruo_only — my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ 21:49
log the boring results too. a channel that only records failures produces a false picture
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the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
98.6 against a certificate of 97.4 is fine. the same supplier landing low four times in a row is a question, n of 1 obviously
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sorry to jump in whats the worst result anyone has logged and what happened next
one data point
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Reminder for rezept_rolf: dose day is today. Set 5 days ago.
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Channel stats, last 30 days: 68 messages from 36 members.
a single sample tells you about a single vial. that is genuinely all it tells you
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is a purity-only test worth the money if underfill is the common failure
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post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
whats the lot
does a bad result on one lot condemn the whole supplier
a supplier disputing a result is rare here and it has never gone well for the supplier
sorry to jump in a result without a lot number and a purchase date is an anecdote with a pdf attached
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
certificate said 98.6 and the independent came back 98.1, is that a problem
i told QYB about a result they would not have liked and they did not argue. credit where it is due
my result contradicts the supplier certificate, do i tell them
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*Janoshik not the other one
genuine question is quantity testing available as a separate thing or bundled
[edited]log the boring ones
how do you post a result so it is actually useful to somebody in a year
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update from 13 months ago: retested the same supplier, result came back better, logged both, thats just me
weigh the vial before you reconstitute. it costs nothing and catches the common failure, i think
update from 24 months ago: retested the same supplier, result came back better, logged both
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
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the honest limits: hobby chain of custody is weak and any result here should be read with that in mind, n of 1 obviously
selection bias
ok so a point or two between the certificate and an independent result is inside what two labs disagree by, still working it out
ok so how much does sample handling on my end affect the number
quick one underfill is more common than impurity. if you only test purity you are testing the less likely failure
i had a result i am fairly sure was a handling error on my side and i logged it as such
thats within range
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which lab
whats the underfill rate people are actually seeing
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
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quantity testing is usually a separate line item and it is the one worth paying for
how many lots do you need before you can say anything about a supplier
i have never regretted spending the money on a test. i have regretted not testing twice
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
if the vial has been through a bad transit you are testing the transit as much as the supplier
my sheet has 6 lots from HJ with a spread under a point, which is tight
is it worth testing if the vial has already been through a warm transit
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm