i have never regretted spending the money on a test. i have regretted not testing twice
#test-results 2025-01-07
Tuesday42 messages7 participantstimes are UTC
Highlights from this day
- sharps_bin_sid — what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern 19:55
- LC_MS_Lena — how do you post a result so it is actually useful to somebody in a year 20:15
- monoisotopic — whats the underfill rate people are actually seeing update from 1 months ago: retested the same supplier, result came back better, logged both 20:27
- cold_pack_carla — log the boring results too. a channel that only records failures produces a false picture 20:59
- LC_MS_Lena — a single sample tells you about a single vial. that is genuinely all it tells you 21:03
a supplier disputing a result is rare here and it has never gone well for the supplier
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does anyone log the negative results, the boring ones
test it again
which lab
what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
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does a bad result on one lot condemn the whole supplier
i test roughly every tenth vial. it is a sampling strategy, not paranoia, someone check my working
whats the worst result anyone has logged and what happened next
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ
how many lots do you need before you can say anything about a supplier
how do you post a result so it is actually useful to somebody in a year
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thats within range
do you test every order or sample it
whats the underfill rate people are actually seeing
update from 1 months ago: retested the same supplier, result came back better, logged both
| 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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is a purity-only test worth the money if underfill is the common failure
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sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
if you are testing to settle an argument you will not settle it with n of 1
quick one how much does sample handling on my end affect the number
attach the pdf
while im here has a supplier ever disputed a result posted here
whats the lot
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log the boring results too. a channel that only records failures produces a false picture
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nice result
a single sample tells you about a single vial. that is genuinely all it tells you
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for the archive the widest spread in my data is about 2.6 percentage points across five lots from one supplier
follow up the honest limits: hobby chain of custody is weak and any result here should be read with that in mind, for what its worth
selection bias
a point or two between the certificate and an independent result is inside what two labs disagree by
one data point
genuine question underfill is more common than impurity. if you only test purity you are testing the less likely failure
a result without a lot number and a purchase date is an anecdote with a pdf attached, ill dig out the number
i had a result i am fairly sure was a handling error on my side and i logged it as such
weigh it first
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one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally
the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
is anyone tracking results over time in a way they would share
posting my Medutest result on lot F-1330, what do people make of it
log the boring ones
update from 17 months ago: retested the same supplier, result came back better, logged both
thats a fill problem
thats not great