#test-results 2026-03-11

selection bias

a point or two between the certificate and an independent result is inside what two labs disagree by

i told SGN about a result they would not have liked and they did not argue. credit where it is due

unrelated but my result contradicts the supplier certificate, do i tell them

one data point

whats the underfill rate people are actually seeing

does a bad result on one lot condemn the whole supplier

update on the earlier thing is it worth testing if the vial has already been through a warm transit

thats not great

thats within range

Verification log updated: QST — evidence added, status unchanged.

coming back after 19 months with a follow up result, where do i put it

which lab

sorry to jump in i have never regretted spending the money on a test. i have regretted not testing twice

sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm

whats the worst result anyone has logged and what happened next
a supplier disputing a result is rare here and it has never gone well for the supplier

i test roughly every tenth vial. it is a sampling strategy, not paranoia

test it again

unrelated but anyone tested the same lot twice at different labs

log the boring ones

how many lots do you need before you can say anything about a supplier

is quantity testing available as a separate thing or bundled

assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem

underfill is more common than impurity. if you only test purity you are testing the less likely failure

slightly off topic but the widest spread in my data is about 2.6 percentage points across five lots from one supplier

my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ, ask me again in a month

my sheet has 2 lots from QSC with a spread under a point, which is tight, i have it written down somewhere

one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally, for what its worth

genuine question what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern

how do you post a result so it is actually useful to somebody in a year

do the results in this channel skew because people test when suspicious

Reminder set. I will post here in 9 days.

when did you buy it

nice result

weigh the vial before you reconstitute. it costs nothing and catches the common failure, anyway

right so i had a result i am fairly sure was a handling error on my side and i logged it as such

posting my PeptideMeter result on lot C-4402, what do people make of it

update from 14 months ago: retested the same supplier, result came back better, logged both

96.8 against a certificate of 99 is fine. the same supplier landing low four times in a row is a question

log the boring results too. a channel that only records failures produces a false picture