99.2 against a certificate of 98.6 is fine. the same supplier landing low four times in a row is a question
#test-results 2025-06-01
Sunday44 messages9 participantstimes are UTC
Highlights from this day
- appetite_back — has a supplier ever disputed a result posted here update from 7 months ago: retested the same supplier, result came back better, logged both 22:24
- assay_not_purity — quick one post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later, from memory 22:49
- ten_of_ten — is it worth testing if the vial has already been through a warm transit 23:04
- VialBot — Verification log updated: SWB — evidence added, status unchanged. 23:15
has a supplier ever disputed a result posted here
update from 7 months ago: retested the same supplier, result came back better, logged both
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quantity testing is usually a separate line item and it is the one worth paying for, ask me again in a month
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally, thats one data point
coming back to this sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
do the results in this channel skew because people test when suspicious
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weigh the vial before you reconstitute. it costs nothing and catches the common failure
certificate said 98.6 and the independent came back 96.8, is that a problem
whats the worst result anyone has logged and what happened next
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
a result without a lot number and a purchase date is an anecdote with a pdf attached
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
update from 16 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
my vial assayed under label but the purity was fine, which matters more
i have never regretted spending the money on a test. i have regretted not testing twice
quick one post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later, from memory
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
whats the lot
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
one data point
is anyone tracking results over time in a way they would share
which lab
if the vial has been through a bad transit you are testing the transit as much as the supplier, your mileage will differ
weigh it first
is it worth testing if the vial has already been through a warm transit
| Evidence | Counts? |
|---|---|
| Independent report, lot you bought, lot number legible | yes |
| Independent report, no lot number | no |
| Supplier certificate only | no |
| Screenshot of a report | no |
| Blinded pooled submission | yes, for the pool |
| A friend who said it was fine | no |
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slightly off topic but my sheet has 7 lots from Homopeptide with a spread under a point, which is tight
a point or two between the certificate and an independent result is inside what two labs disagree by
log the boring results too. a channel that only records failures produces a false picture, i have it written down somewhere
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Verification log updated: SWB — evidence added, status unchanged.
does anyone log the negative results, the boring ones
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underfill is more common than impurity. if you only test purity you are testing the less likely failure
[edited]how much does sample handling on my end affect the number
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ok so does a bad result on one lot condemn the whole supplier
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
a supplier disputing a result is rare here and it has never gone well for the supplier, thats just me
a result without a lot number and a purchase date is an anecdote with a pdf attached
nice result
anyone had a result they think was a lab error rather than a bad vial
my result contradicts the supplier certificate, do i tell them
for the archive is a purity-only test worth the money if underfill is the common failure
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
i test roughly every tenth vial. it is a sampling strategy, not paranoia
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
a single sample tells you about a single vial. that is genuinely all it tells you
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