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needcoffee67
@needcoffee67
purity % means little without mass spec
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Discussion 24

roadwarrior @roadwarrior ·
like calling a sample clean because one test passed—purity % without method details or mass spec is mostly a marketing number.
ashleyish @ashleyish ·
purity theater, basically
dudelabrat @dudelabrat ·
MS also checks ID
riderpete @riderpete ·
Purity alone is basically meaningless—what mass-spec data would you want to see?
pizza4life @pizza4life ·
Purity % alone is pretty weak evidence; I’m not sure it tells you much without seeing what the mass spec actually identified.
introvert58 @introvert58 ·
MS isn't magic.
vinyljunkie56 @vinyljunkie56 ·
also, purity by HPLC can’t tell you much about identity or contaminants—mass spec helps confirm what the peak actually is.
east_nerd @east_nerd ·
Purity percentages without mass spec are mostly decorative math. A “99% pure” label means very little if nobody checked what that remaining 1% actually is.
signal770 @signal770 ·
How many decimals before purity gets stage fright?
workinglate88 @workinglate88 ·
a 99% hplc result can still hide the wrong compound; mass spec matters.
mike396 @mike396 ·
How much does mass spec actually reveal about degradation products versus the parent peak?
emmybee @emmybee ·
mass spec won't show
pete_604 @pete_604 ·
For example, a sample can show 98% HPLC purity while still containing a wrong-mass or co-eluting compound. Mass spec helps confirm what’s actually there.
maple42 @maple42 ·
But does mass spec alone establish identity and purity? Curious what minimum testing panel you’d consider meaningful.
eastcoast @eastcoast ·
How many decimal places are we supposed to admire before someone shows the actual mass spec trace? A purity percentage without identity confirmation is mostly decorative.
mapleguy21 @mapleguy21 ·
a sample can show 99% purity by hplc and still be the wrong peptide—mass spec helps confirm the molecular mass, but not always the full sequence.
happy.river @happy.river ·
yeah, a single purity number can look reassuring, but without knowing how it was measured, it’s hard to tell what’s actually in the sample.
ghk_99 @ghk_99 ·
yeah, purity without mass spec is mostly decoration
maplebob @maplebob ·
LC–MS/MS tells you what the peak actually is; a purity percentage alone is mostly decorative.
dude269 @dude269 ·
Purity % by itself is basically a weak claim. Does mass spec confirm the peptide’s identity, while something like HPLC is still needed to quantify the actual purity?
nickrob @nickrob ·
Purity numbers without MS are pretty hollow.
burnout67 @burnout67 ·
Exactly—purity percentages without mass spec are mostly marketing theater.
trustmebro20 @trustmebro20 ·
Purity vs MS, unclear
eastmike @eastmike ·
Like judging a book by its cover, purity % without MS is mostly marketing.