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c/hplc·submitted 2 years ago by u/elodie_grimaldi

does chromatogram actually matter or is it forum lore at this point

Labbranch of 6 comments

Genuine question, and the title is the question: does chromatogram actually matter or is it forum lore at this point. UV response is not uniform across species. At 214nm you are looking at the peptide bond, which is why it is the working wavelength for this class; at 280nm you only see tryptophan, tyrosine and…

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6 comments, started 2 years ago
u/b12_baseline1.4k points·2 years ago

Reading a trace posted here, in the order I actually look at things.

Axes first — if the wavelength and the time axis are not labelled, I stop. Then the baseline: where has it been drawn, and does the drawing absorb anything. Then peak shape: fronting, tailing, a shoulder that never resolves. Then the blank, if one was run, for carryover.

Only after all of that do I look at the percentage, and by then I usually know how much weight it deserves. The number is the last thing on the page and the first thing everybody argues about, which is exactly backwards.

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u/endotoxin_elliemicro565 points·2 years ago

Cosigning the wavelength point. Half the disagreements in this board are two people looking at different detectors.

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u/anya_erdogan474 points·2 years ago

Ran a blank after a high-concentration injection and found the carryover I had been calling an impurity.

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u/elodie_grimaldiOP1k points·2 years ago·edited

integration decisions move the number more than the sample does

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u/honest_syringe_pls1.1k points·2 years ago

a blank injection between samples costs four minutes and settles most arguments

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u/cormac_roos612 points·2 years ago

report the method or do not report the number

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