i test roughly every tenth vial. it is a sampling strategy, not paranoia
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#test-results 2026-02-05
Thursday54 messages11 participantstimes are UTC
Highlights from this day
- VialBot — New independent result logged — KP, lot A-2418, purity 98.6% (PeptideMeter). 07:47
- salt_bridge — how many lots do you need before you can say anything about a supplier 09:26
- chlorhex — update on the earlier thing my sheet has 8 lots from WWB with a spread under a point, which is tight, i have it written down somewhere 10:33
i told WWB about a result they would not have liked and they did not argue. credit where it is due
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
how do you separate batch variance from supplier variance
log the boring ones
Purity check: no report on file for lot F-1330. Nothing logged either way.
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
has a supplier ever disputed a result posted here
update from 5 months ago: retested the same supplier, result came back better, logged both
which lab
attach the pdf
| 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 |
is it worth testing if the vial has already been through a warm transit
weigh it first
a supplier disputing a result is rare here and it has never gone well for the supplier
right so whats the underfill rate people are actually seeing
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New independent result logged — KP, lot A-2418, purity 98.6% (PeptideMeter).
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thats not great
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if you are testing to settle an argument you will not settle it with n of 1
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
when did you buy it
test it again
how do you post a result so it is actually useful to somebody in a year
a result without a lot number and a purchase date is an anecdote with a pdf attached
whats the lot
log the lot number
is quantity testing available as a separate thing or bundled
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
i have never regretted spending the money on a test. i have regretted not testing twice
is anyone tracking results over time in a way they would share
thats a fill problem
how many lots do you need before you can say anything about a supplier
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unrelated but i had a result i am fairly sure was a handling error on my side and i logged it as such, still working it out
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thats within range
nice result
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for the archive a single sample tells you about a single vial. that is genuinely all it tells you
one data point
my vial assayed under label but the purity was fine, which matters more
update on the earlier thing my sheet has 8 lots from WWB with a spread under a point, which is tight, i have it written down somewhere
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anyone had a result they think was a lab error rather than a bad vial
Assay note: SGN lot G-0641 reported at 96.8% of label content.
99.4 against a certificate of 97.4 is fine. the same supplier landing low four times in a row is a question
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
genuine question posting my Janoshik result on lot E-2205, what do people make of it
do you test every order or sample it
anyone tested the same lot twice at different labs
does a bad result on one lot condemn the whole supplier
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if the vial has been through a bad transit you are testing the transit as much as the supplier
certificate said 97.4 and the independent came back 96.8, is that a problem
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unrelated but underfill is more common than impurity. if you only test purity you are testing the less likely failure
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
sorry to jump in one data point
i had a result i am fairly sure was a handling error on my side and i logged it as such
a point or two between the certificate and an independent result is inside what two labs disagree by