does a bad result on one lot condemn the whole supplier
#test-results 2025-12-03
Wednesday52 messages12 participantstimes are UTC
Highlights from this day
- per_mg_pete — a single sample tells you about a single vial. that is genuinely all it tells you 21:19
- per_mg_pete — what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern one bad test does not condemn a supplier. one good test… 21:47
- noct.titrate — one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally 23:02
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
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post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
when did you buy it
a supplier disputing a result is rare here and it has never gone well for the supplier
update on the earlier thing is a purity-only test worth the money if underfill is the common failure
thats not great
weigh the vial before you reconstitute. it costs nothing and catches the common failure
a single sample tells you about a single vial. that is genuinely all it tells you
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 / 10mg🔥1📉8
which lab
if you are testing to settle an argument you will not settle it with n of 1
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nice result
i had a result i am fairly sure was a handling error on my side and i logged it as such, someone check my working
one data point
selection bias
quantity testing is usually a separate line item and it is the one worth paying for
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
New independent result logged — CPC, lot H-2814, purity 99.4% (VendorInvestigate).
update from 24 months ago: retested the same supplier, result came back better, logged both
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
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 / 10mgassay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
weigh it first
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log the boring ones
coming back after 14 months with a follow up result, where do i put it
is anyone tracking results over time in a way they would share
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while im here is it worth testing if the vial has already been through a warm transit
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how much does sample handling on my end affect the number
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a point or two between the certificate and an independent result is inside what two labs disagree by
[edited]my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
posting my PeptideMeter result on lot E-2205, what do people make of it
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unrelated but is quantity testing available as a separate thing or bundled
my sheet has 3 lots from CPC with a spread under a point, which is tight
[edited]the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
*PeptideMeter not the other one
ok so do you test every order or sample it
whats the worst result anyone has logged and what happened next
thats within range
how do you post a result so it is actually useful to somebody in a year
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how many lots do you need before you can say anything about a supplier
whats the lot
update on the earlier thing i test roughly every tenth vial. it is a sampling strategy, not paranoia
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ok so the widest spread in my data is about 2.6 percentage points across five lots from one supplier
Purity check: no report on file for lot A-2601. Nothing logged either way.
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i told TFC about a result they would not have liked and they did not argue. credit where it is due
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
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log the lot number
follow up test it again
a result without a lot number and a purchase date is an anecdote with a pdf attached
selection bias
one data point
attach the pdf
underfill is more common than impurity. if you only test purity you are testing the less likely failure
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