the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
#test-results 2025-04-14
Monday38 messages10 participantstimes are UTC
Highlights from this day
- HPLC_Hank — my vial assayed under label but the purity was fine, which matters more 14:59
- VialBot — Assay note: KP lot H-2814 reported at 98.1% of label content. 15:27
- blind_submit — my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ 19:12
- noct.titrate — quantity testing is usually a separate line item and it is the one worth paying for 19:19
thats not great
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
genuine question sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
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weigh the vial before you reconstitute. it costs nothing and catches the common failure
do the results in this channel skew because people test when suspicious
do you test every order or sample it
weights-monthly.csv
585 rows · not retained in the public archive
certificate said 96.8 and the independent came back 99, is that a problem
i have never regretted spending the money on a test. i have regretted not testing twice
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
my vial assayed under label but the purity was fine, which matters more
| Evidence | Counts? |
|---|---|
| Independent report, lot you bought, lot number legible | yes |
| Independent report, no lot number | no |
| Supplier certificate only | no |
| Screenshot of a report | no |
| Blinded pooled submission | yes, for the pool |
| A friend who said it was fine | no |
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
is quantity testing available as a separate thing or bundled
if you are testing to settle an argument you will not settle it with n of 1, from memory
Assay note: KP lot H-2814 reported at 98.1% of label content.
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a point or two between the certificate and an independent result is inside what two labs disagree by
log the boring results too. a channel that only records failures produces a false picture
update from 21 months ago: retested the same supplier, result came back better, logged both
how do you separate batch variance from supplier variance
a result without a lot number and a purchase date is an anecdote with a pdf attached
a supplier disputing a result is rare here and it has never gone well for the supplier
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
attach the pdf
underfill is more common than impurity. if you only test purity you are testing the less likely failure
if the vial has been through a bad transit you are testing the transit as much as the supplier
[edited]unrelated but a single sample tells you about a single vial. that is genuinely all it tells you
ok so is anyone tracking results over time in a way they would share
log the boring results too. a channel that only records failures produces a false picture
anyone had a result they think was a lab error rather than a bad vial
whats the lot
i told FGP about a result they would not have liked and they did not argue. credit where it is due
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
i had a result i am fairly sure was a handling error on my side and i logged it as such
i test roughly every tenth vial. it is a sampling strategy, not paranoia
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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thats within range
selection bias
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assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
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quantity testing is usually a separate line item and it is the one worth paying for
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thats a fill problem