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c/hplc·submitted 17 days ago by u/ignacio_vanhecke

[Lab] LC-MS confirmed identity but the UV purity is 94%. now what

Labbranch of 8 comments

LC-MS confirmed identity but the UV purity is 94%. now what, and before anyone asks: same batch throughout, single submission, no cherry-picking between services. The relevant figures are 94%, and they come from the same log I have kept the whole time. Started reporting my own integrations with the baseline choice…

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8 comments, started 16 days ago
u/coa_janitormod · c/coa24 points·16 days ago

Resolution between two peaks depends on retention, selectivity and efficiency. A shallower gradient buys retention and usually resolution, at the cost of peak width and run time.

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u/ignacio_vanheckeOP13 points·16 days ago

Correcting myself upthread: I said the gradient was linear and looking again it has a hold in the middle.

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u/saskia_bakker3 points·16 days ago

ghost peak, check the plumbing first, it is always the plumbing

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u/ahmed_rasmussen6 points·16 days ago

area percent is relative to what the detector saw and nothing else

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u/blunt_coldbox_20244 points·16 days ago

What did system suitability look like on that sequence?

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u/bilal_adebayo2 points·15 days ago·edited

214nm sees the peptide bond, 280nm sees the aromatics

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u/zeynep_zielinski4 points·16 days ago·edited

area percent is relative to what the detector saw and nothing else

ahmed_rasmussen is right — the integration choice is a decision and it should be stated alongside the result.

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u/egfr_watcher2 points·16 days ago

Right. And a blank between injections settles the carryover argument before it starts.

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