my result contradicts the supplier certificate, do i tell them
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#test-results 2024-11-30
Saturday37 messages9 participantstimes are UTC
Highlights from this day
- maintenance_mo — i told GL Biochem about a result they would not have liked and they did not argue. credit where it is due a supplier disputing a result is rare here and it has never… 18:10
- LC_MS_Lena — how do you separate batch variance from supplier variance 18:22
- verify_or_dont — whats the worst result anyone has logged and what happened next 19:37
- area_percent — i test roughly every tenth vial. it is a sampling strategy, not paranoia 20:00
a point or two between the certificate and an independent result is inside what two labs disagree by
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
how do you post a result so it is actually useful to somebody in a year
log the boring results too. a channel that only records failures produces a false picture
thats a fill problem
i told GL Biochem about a result they would not have liked and they did not argue. credit where it is due
a supplier disputing a result is rare here and it has never gone well for the supplier
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later, for what its worth
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how do you separate batch variance from supplier variance
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whats the lot
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99 against a certificate of 96.8 is fine. the same supplier landing low four times in a row is a question, thats one data point
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
i have never regretted spending the money on a test. i have regretted not testing twice
is a purity-only test worth the money if underfill is the common failure
has a supplier ever disputed a result posted here
coming back after 23 months with a follow up result, where do i put it
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
thats not great
whats the worst result anyone has logged and what happened next
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anyone tested the same lot twice at different labs
anyone had a result they think was a lab error rather than a bad vial
does a bad result on one lot condemn the whole supplier
i had a result i am fairly sure was a handling error on my side and i logged it as such
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
is anyone tracking results over time in a way they would share
i test roughly every tenth vial. it is a sampling strategy, not paranoia
| 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 |
thats within range
coming back to this my sheet has 4 lots from GGPeps with a spread under a point, which is tight
if you are testing to settle an argument you will not settle it with n of 1
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
weigh it first
posting my Medutest result on lot SG-1177, what do people make of it
while im here is it worth testing if the vial has already been through a warm transit
Inter-lab diff for lot KP-0925: 98.1% vs 97.4%. Within expected range.
attach the pdf
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a single sample tells you about a single vial. that is genuinely all it tells you
when did you buy it
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