has a supplier ever disputed a result posted here
#test-results 2026-02-18
Wednesday39 messages8 participantstimes are UTC
Highlights from this day
- quiet_head_qi — post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later 13:12
- HPLC_Hank — sorry to jump in if you are testing to settle an argument you will not settle it with n of 1 14:11
- impersonator_ip — a point or two between the certificate and an independent result is inside what two labs disagree by what interests me is when the gap goes the same direction every… 15:58
- quiet_head_qi — how much does sample handling on my end affect the number 16:45
- HPLC_Hank — i told BCH about a result they would not have liked and they did not argue. credit where it is due 17:44
i have never regretted spending the money on a test. i have regretted not testing twice, anyway
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my result contradicts the supplier certificate, do i tell them
if you are testing to settle an argument you will not settle it with n of 1
do the results in this channel skew because people test when suspicious
quantity testing is usually a separate line item and it is the one worth paying for
update from 4 months ago: retested the same supplier, result came back better, logged both
how do you post a result so it is actually useful to somebody in a year
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selection bias
how do you separate batch variance from supplier variance
slightly off topic but anyone tested the same lot twice at different labs
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
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96.8 against a certificate of 98.1 is fine. the same supplier landing low four times in a row is a question
which lab
log the boring results too. a channel that only records failures produces a false picture, i could be wrong
log the lot number
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attach the pdf
i test roughly every tenth vial. it is a sampling strategy, not paranoia
[edited]how many lots do you need before you can say anything about a supplier
slightly off topic but weigh the vial before you reconstitute. it costs nothing and catches the common failure
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
sorry to jump in if you are testing to settle an argument you will not settle it with n of 1
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does anyone log the negative results, the boring ones
a supplier disputing a result is rare here and it has never gone well for the supplier
coming back after 8 months with a follow up result, where do i put it
if the vial has been through a bad transit you are testing the transit as much as the supplier
is a purity-only test worth the money if underfill is the common failure
one data point
thats a fill problem
nice result
follow up assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
a point or two between the certificate and an independent result is inside what two labs disagree by
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern, we shall see
slightly off topic but underfill is more common than impurity. if you only test purity you are testing the less likely failure, from memory
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
test it again
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 / 10mgis anyone tracking results over time in a way they would share
*Medutest not the other one
i told BCH about a result they would not have liked and they did not argue. credit where it is due