anyone had a result they think was a lab error rather than a bad vial
#test-results 2025-12-09
Tuesday54 messages11 participantstimes are UTC
Highlights from this day
- rotate_the_site — coming back to this 99 against a certificate of 99.2 is fine. the same supplier landing low four times in a row is a question 13:34
- cat_on_the_tray — posting my PeptideMeter result on lot A-2418, what do people make of it 13:37
- charge_state — update on the earlier thing how do you separate batch variance from supplier variance 15:25
- lead_time_lars — genuine question the honest limits: hobby chain of custody is weak and any result here should be read with that in mind 16:46
- coa_or_cope — a point or two between the certificate and an independent result is inside what two labs disagree by, for what its worth 18:48
thats not great
[edited]selection bias
one data point
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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
how much does sample handling on my end affect the number
underfill is more common than impurity. if you only test purity you are testing the less likely failure
if you are testing to settle an argument you will not settle it with n of 1
how do you post a result so it is actually useful to somebody in a year
update from 11 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
is anyone tracking results over time in a way they would share
peptidemeter-summary-f-1330.pdf
2 pages · 414 KB · not retained in the public archive
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log the boring ones
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which lab
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
*PeptideMeter not the other one
i have never regretted spending the money on a test. i have regretted not testing twice
thats within range
attach the pdf
coming back to this 99 against a certificate of 99.2 is fine. the same supplier landing low four times in a row is a question
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a single sample tells you about a single vial. that is genuinely all it tells you, thats one data point
posting my PeptideMeter result on lot A-2418, what do people make of it
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coming back to this a result without a lot number and a purchase date is an anecdote with a pdf attached, thats just me
a supplier disputing a result is rare here and it has never gone well for the supplier
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coming back after 3 months with a follow up result, where do i put it
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
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
whats the worst result anyone has logged and what happened next
thats a fill problem
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real, from memory
while im here do you test every order or sample it
i told CPC about a result they would not have liked and they did not argue. credit where it is due
weigh the vial before you reconstitute. it costs nothing and catches the common failure
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*Janoshik not the other one
ok so my result contradicts the supplier certificate, do i tell them
sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
does a bad result on one lot condemn the whole supplier
quantity testing is usually a separate line item and it is the one worth paying for
has a supplier ever disputed a result posted here
update on the earlier thing how do you separate batch variance from supplier variance
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nice result
log the boring results too. a channel that only records failures produces a false picture
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ, thats just me
certificate said 99.4 and the independent came back 99, is that a problem
genuine question the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
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anyone tested the same lot twice at different labs
a supplier disputing a result is rare here and it has never gone well for the supplier, ymmv
my sheet has 5 lots from GGPeps with a spread under a point, which is tight
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ok so my vial assayed under label but the purity was fine, which matters more
if the vial has been through a bad transit you are testing the transit as much as the supplier, ask me again in a month
when did you buy it
[edited]a point or two between the certificate and an independent result is inside what two labs disagree by, for what its worth
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one data point, thats just me
do the results in this channel skew because people test when suspicious
whats the lot