#test-results 2025-11-21

a result without a lot number and a purchase date is an anecdote with a pdf attached

underfill is more common than impurity. if you only test purity you are testing the less likely failure

what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern

nice result

log the boring ones

follow up is quantity testing available as a separate thing or bundled

has a supplier ever disputed a result posted here

does anyone log the negative results, the boring ones

my result contradicts the supplier certificate, do i tell them

thats a fill problem

the widest spread in my data is about 2.6 percentage points across five lots from one supplier

98.6 against a certificate of 99.2 is fine. the same supplier landing low four times in a row is a question

i test roughly every tenth vial. it is a sampling strategy, not paranoia

when did you buy it

result came back 94.2% and i am fairly sure it is my fault not theirs

go on

posted the sample in July, it sat in a sorting depot for six days, tracking showed it in a country i have never been to, and the lab logged it as received eleven days after i sent it

reconstituted or dry powder

dry

then you are probably fine actually. dry lyophilised peptide is far more robust than people assume, that is the whole point of lyophilising it

so 94.2 is real

94.2 is probably real, or at least the heat is not the obvious explanation. eleven days dry at ambient does not usually cost you five points

it does if humidity got in. did you send the whole vial or decant

decanted into an eppendorf

there it is. how long was the vial open

couple of minutes, kitchen, summer

then some water went in with it. probably not five points worth but it is a real contributor and it is entirely on our side of the line

this is the hobby chain-of-custody problem in one story. the lab did its job perfectly and the number still does not mean what we want it to mean

so how are you supposed to send a sample

short version, and none of it is clever

sending the sealed vial feels wasteful

it is wasteful. it is also the only version where a low result means something

we have had this argument about twenty times and it always lands there

does the lab care which way you send it

labs will test what arrives. they may note the container. they will not reconstruct your kitchen for you

the Saber sample i sent went as a sealed vial and the report noted vial intact, cake white and free-flowing, which was worth having on paper

that is point four on your list from the other side. the lab writes down what we should have photographed

my report says appearance: white powder, no comment on the cake because there was no cake, it was a scoop in a tube

right. and that is a small piece of information you destroyed by decanting

im going to reread this before i send anything

also declare it properly. mine went as analytical reference sample, no commercial value, and cleared without a question

mine said peptide sample and it got opened

wording matters more than it should. more on that in #lab-requests and #shipping-customs

and to close the loop on the original number: i would call 94.2 unusable rather than bad. you cannot attribute it

which is annoying but fair. sending a sealed one from the same order next month

post both when you have them, a paired result on the same order is worth more than either alone