my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
#test-results 2026-02-28
Saturday24 messages7 participantstimes are UTC
Highlights from this day
- nhs_pathway_nell — quick one the widest spread in my data is about 2.6 percentage points across five lots from one supplier a single sample tells you about a single vial. that is… 16:54
- cat_on_the_tray — quantity testing is usually a separate line item and it is the one worth paying for 17:03
- lean_mass_lex — a single sample tells you about a single vial. that is genuinely all it tells you 19:17
- VialBot — New independent result logged — ERP, lot B-0329, purity 98.6% (PeptideMeter). 19:25
- monoisotopic — the results in this channel skew because people test when they are suspicious. that is selection bias and it is real 20:09
thats within range
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem, n of 1 obviously
weigh it first
[edited]quick one the widest spread in my data is about 2.6 percentage points across five lots from one supplier
a single sample tells you about a single vial. that is genuinely all it tells you
| 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 |
quantity testing is usually a separate line item and it is the one worth paying for
| 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 |
a supplier disputing a result is rare here and it has never gone well for the supplier, not advice obviously
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
[edited]certificate said 99 and the independent came back 99.4, is that a problem
selection bias
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post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
log the boring ones
my result contradicts the supplier certificate, do i tell them
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
fridge-thermometer.png
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whats the lot
if the vial has been through a bad transit you are testing the transit as much as the supplier
a point or two between the certificate and an independent result is inside what two labs disagree by
thats a fill problem
[edited]test it again
a single sample tells you about a single vial. that is genuinely all it tells you
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weigh the vial before you reconstitute. it costs nothing and catches the common failure, i have it written down somewhere
New independent result logged — ERP, lot B-0329, purity 98.6% (PeptideMeter).
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
| 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 |
anyone had a result they think was a lab error rather than a bad vial
quick one do you test every order or sample it
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