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c/hplc·submitted 2 months ago by u/b12_baseline

help me understand gradient, I have read the wiki twice

Methodbranch of 8 comments

help me understand gradient, I have read the wiki twice, and I want the answer with the reasoning attached rather than just the conclusion. Why two honest labs report different numbers on the same vial. Start with the gradient. A shallower slope holds compounds on the column longer and usually separates close-eluting…

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8 comments, started 2 months ago
u/saskia_bakker133 points·2 months ago

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

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u/andres_restrepo53 points·2 months ago

report the method or do not report the number

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u/zeynep_zielinski18 points·2 months ago

LC-MS for identity, UV for relative quantity

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u/arne_nyberg26 points·2 months ago

Bought a second-hand instrument and learned more in six months of fixing it than in three years of reading traces.

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u/aksel_palacios-18 points·2 months ago

the column has a history and it shows in the peak shape

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u/blunt_coldbox_20240 points·2 months ago

Correction: that is a tailing factor, not a plate count. Different diagnostics for different problems.

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u/camila_lindqvist1 point·2 months ago

retention time alone is not identity

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u/rania_okonkwo0 points·2 months ago

Retention time shifted 0.4 minutes and I assumed the worst. It was the column temperature.

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