sorry to jump in a supplier disputing a result is rare here and it has never gone well for the supplier
#test-results 2025-11-19
Wednesday21 messages7 participantstimes are UTC
Highlights from this day
- fasting_insulin — slightly off topic but my sheet has 6 lots from MKM with a spread under a point, which is tight 12:04
- taper_tess — how do you separate batch variance from supplier variance 12:41
- confirmations_six — is a purity-only test worth the money if underfill is the common failure 13:50
- confirmations_six — the widest spread in my data is about 2.6 percentage points across five lots from one supplier, thats one data point 15:38
a single sample tells you about a single vial. that is genuinely all it tells you
slightly off topic but my sheet has 6 lots from MKM with a spread under a point, which is tight
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally, ill dig out the number
thats a fill problem
attach the pdf
log the boring results too. a channel that only records failures produces a false picture
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
underfill is more common than impurity. if you only test purity you are testing the less likely failure
which lab
weigh it first
how do you separate batch variance from supplier variance
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my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
i test roughly every tenth vial. it is a sampling strategy, not paranoia
ok so sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
thats within range
update on the earlier thing 99 against a certificate of 96.8 is fine. the same supplier landing low four times in a row is a question
is a purity-only test worth the money if underfill is the common failure
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a point or two between the certificate and an independent result is inside what two labs disagree by, i think
right so i have never regretted spending the money on a test. i have regretted not testing twice
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
the widest spread in my data is about 2.6 percentage points across five lots from one supplier, thats one data point
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