99.4 against a certificate of 96.8 is fine. the same supplier landing low four times in a row is a question
#test-results 2025-11-01
Saturday62 messages11 participantstimes are UTC
Highlights from this day
Inter-lab diff for lot H-2814: 99% vs 99.2%. Within expected range.
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slightly off topic but whats the worst result anyone has logged and what happened next
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
is a purity-only test worth the money if underfill is the common failure
whats the lot
slightly off topic but i have never regretted spending the money on a test. i have regretted not testing twice
has a supplier ever disputed a result posted here
one data point
when did you buy it
does a bad result on one lot condemn the whole supplier
log the boring ones
quantity testing is usually a separate line item and it is the one worth paying for
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my sheet has 2 lots from WWB with a spread under a point, which is tight
On this day 8 years ago this channel logged 27 messages.
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the widest spread in my data is about 2.6 percentage points across five lots from one supplier, n of 1 obviously
nice result
if you are testing to settle an argument you will not settle it with n of 1
how many lots do you need before you can say anything about a supplier
log the lot number
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weigh it first
do you test every order or sample it
while im here sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
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 / 10mgthats within range
while im here if the vial has been through a bad transit you are testing the transit as much as the supplier
right so is it worth testing if the vial has already been through a warm transit
is quantity testing available as a separate thing or bundled
a single sample tells you about a single vial. that is genuinely all it tells you
thats not great
attach the pdf
slightly off topic but post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
Inter-lab diff for lot D-0718: 99% vs 98.1%. Within expected range.
ok so how do you post a result so it is actually useful to somebody in a year
while im here what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
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On this day 8 years ago this channel logged 91 messages.
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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
anyone tested the same lot twice at different labs
posting my PeptideMeter result on lot B-0329, what do people make of it
a result without a lot number and a purchase date is an anecdote with a pdf attached
a point or two between the certificate and an independent result is inside what two labs disagree by
*Janoshik not the other one
which lab
quick one a supplier disputing a result is rare here and it has never gone well for the supplier
medutest-report-h-2814.pdf
3 pages · 701 KB · not retained in the public archive
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i had a result i am fairly sure was a handling error on my side and i logged it as such, thats just me
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
selection bias
right so underfill is more common than impurity. if you only test purity you are testing the less likely failure
Inter-lab diff for lot C-4402: 98.6% vs 99.2%. Within expected range.
for the archive is anyone tracking results over time in a way they would share
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does anyone log the negative results, the boring ones
i test roughly every tenth vial. it is a sampling strategy, not paranoia
right so coming back after 9 months with a follow up result, where do i put it
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 / 10mgthats a fill problem, ask me again in a month
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weigh the vial before you reconstitute. it costs nothing and catches the common failure, thats one data point
log the boring results too. a channel that only records failures produces a false picture
my sheet has 9 lots from GL Biochem with a spread under a point, which is tight
test it again
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whats the underfill rate people are actually seeing
nice result
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real, from memory
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follow up update from 1 months ago: retested the same supplier, result came back better, logged both, i think
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
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how much does sample handling on my end affect the number