my result contradicts the supplier certificate, do i tell them
#test-results 2025-09-14
Sunday58 messages15 participantstimes are UTC
Highlights from this day
- ms_ms_mira — a supplier disputing a result is rare here and it has never gone well for the supplier 19:43
- ms_ms_mira — does anyone log the negative results, the boring ones 19:48
- orfor_watch — does a bad result on one lot condemn the whole supplier 21:50
- confirmations_six — the widest spread in my data is about 2.6 percentage points across five lots from one supplier 22:08
- escalation_anxiety — the honest limits: hobby chain of custody is weak and any result here should be read with that in mind 22:44
is it worth testing if the vial has already been through a warm transit
anyone tested the same lot twice at different labs
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test it again
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
update from 7 months ago: retested the same supplier, result came back better, logged both
if you are testing to settle an argument you will not settle it with n of 1
weigh the vial before you reconstitute. it costs nothing and catches the common failure
a supplier disputing a result is rare here and it has never gone well for the supplier
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does anyone log the negative results, the boring ones
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99.4 against a certificate of 99.2 is fine. the same supplier landing low four times in a row is a question
[edited]sorry to jump in how much does sample handling on my end affect the number
follow up i told TFC about a result they would not have liked and they did not argue. credit where it is due
nice result
i test roughly every tenth vial. it is a sampling strategy, not paranoia
sorry to jump in log the boring results too. a channel that only records failures produces a false picture
how do you separate batch variance from supplier variance
[edited]Digest for the week of 2025-04-21 has been published.
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind, anyway
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
certificate said 98.1 and the independent came back 99.2, is that a problem
posting my VendorInvestigate result on lot SG-1177, what do people make of it
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
when did you buy it
is anyone tracking results over time in a way they would share
one data point
has a supplier ever disputed a result posted here
a single sample tells you about a single vial. that is genuinely all it tells you, happy to be corrected
i had a result i am fairly sure was a handling error on my side and i logged it as such
quick one underfill is more common than impurity. if you only test purity you are testing the less likely failure
whats the underfill rate people are actually seeing
a result without a lot number and a purchase date is an anecdote with a pdf attached
Inter-lab diff for lot KP-0925: 97.4% vs 99.2%. Within expected range.
unrelated but a point or two between the certificate and an independent result is inside what two labs disagree by, i have it written down somewhere
thats a fill problem
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
update from 18 months ago: retested the same supplier, result came back better, logged both
*Medutest not the other one
is a purity-only test worth the money if underfill is the common failure
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log the boring ones
quantity testing is usually a separate line item and it is the one worth paying for, your mileage will differ
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post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
my sheet has 9 lots from Homopeptide with a spread under a point, which is tight, take that with a pinch of salt
which lab
does a bad result on one lot condemn the whole supplier
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coming back after 14 months with a follow up result, where do i put it
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem, for what its worth
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i have never regretted spending the money on a test. i have regretted not testing twice, from memory
whats the worst result anyone has logged and what happened next
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
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if the vial has been through a bad transit you are testing the transit as much as the supplier
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attach the pdf
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do you test every order or sample it
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sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm, happy to be corrected
a supplier disputing a result is rare here and it has never gone well for the supplier
selection bias
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is quantity testing available as a separate thing or bundled
thats within range, from memory
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
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