for the archive anyone had a result they think was a lab error rather than a bad vial
#test-results 2025-02-01
Saturday27 messages8 participantstimes are UTC
Highlights from this day
- fake_tracking — a result without a lot number and a purchase date is an anecdote with a pdf attached 20:23
- nhs_pathway_nell — while im here underfill is more common than impurity. if you only test purity you are testing the less likely failure, ymmv 21:26
- nhs_pathway_nell — one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally 21:28
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
update on the earlier thing has a supplier ever disputed a result posted here
whats the worst result anyone has logged and what happened next
*Medutest not the other one
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern, someone check my working
i had a result i am fairly sure was a handling error on my side and i logged it as such, i have it written down somewhere
my sheet has 2 lots from Homopeptide with a spread under a point, which is tight
whats the lot
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 / 10mga result without a lot number and a purchase date is an anecdote with a pdf attached
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one data point
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
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post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
test it again
selection bias
[edited]slightly off topic but a single sample tells you about a single vial. that is genuinely all it tells you
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
Recon calculator: 2mg in 5ml = 5mg/ml.
99.2 against a certificate of 98.1 is fine. the same supplier landing low four times in a row is a question
while im here underfill is more common than impurity. if you only test purity you are testing the less likely failure, ymmv
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one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
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whats the underfill rate people are actually seeing
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if the vial has been through a bad transit you are testing the transit as much as the supplier
is anyone tracking results over time in a way they would share
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log the boring results too. a channel that only records failures produces a false picture
update from 7 months ago: retested the same supplier, result came back better, logged both, ymmv
thats not great