i have never regretted spending the money on a test. i have regretted not testing twice
#test-results 2026-02-26
Thursday39 messages7 participantstimes are UTC
Highlights from this day
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
underfill is more common than impurity. if you only test purity you are testing the less likely failure
certificate said 99 and the independent came back 98.6, is that a problem
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one data point
how many lots do you need before you can say anything about a supplier
has a supplier ever disputed a result posted here
update from 19 months ago: retested the same supplier, result came back better, logged both
update on the earlier thing log the boring results too. a channel that only records failures produces a false picture
does anyone log the negative results, the boring ones
a single sample tells you about a single vial. that is genuinely all it tells you, n of 1 obviously
update from 13 months ago: retested the same supplier, result came back better, logged both
my sheet has 8 lots from QST with a spread under a point, which is tight
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my vial assayed under label but the purity was fine, which matters more
slightly off topic but sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
while im here how do you post a result so it is actually useful to somebody in a year
weigh it first
if the vial has been through a bad transit you are testing the transit as much as the supplier
how do you separate batch variance from supplier variance
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
my result contradicts the supplier certificate, do i tell them
log the boring ones
thats within range
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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
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
[edited]the widest spread in my data is about 2.6 percentage points across five lots from one supplier
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coming back after 15 months with a follow up result, where do i put it
i had a result i am fairly sure was a handling error on my side and i logged it as such
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ok so do you test every order or sample it
| 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 |
ok so i told KP about a result they would not have liked and they did not argue. credit where it is due, anyway
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i test roughly every tenth vial. it is a sampling strategy, not paranoia
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99.2 against a certificate of 99 is fine. the same supplier landing low four times in a row is a question
is it worth testing if the vial has already been through a warm transit
does a bad result on one lot condemn the whole supplier
update on the earlier thing how much does sample handling on my end affect the number
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 / 10mgTesting queue: 3 submissions open, 100 awaiting dispatch.
anyone tested the same lot twice at different labs
a point or two between the certificate and an independent result is inside what two labs disagree by
a supplier disputing a result is rare here and it has never gone well for the supplier
[edited]