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c/hplc·submitted 11 months ago by u/endotoxin_ellie

21 months in and HPLC is still the thing I get wrong

Explainerbranch of 6 comments

Genuinely asking, not being difficult. Everyone in c/glp1uk repeats that chromatogram is important. I believe it, but I have never seen anyone show why, and when I search I get 21 threads of people agreeing with each other. Is there a paper? Is there a measurement? Or is this one of those things that is true because…

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6 comments, started 11 months ago
u/adaeze_batista414 points·11 months ago

Yeah, the chromatogram profile matters more than the headline number.

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u/yara_bakken278 points·11 months ago

Yeah, the chromatogram profile matters more than the headline number.

Disagree on that part. 98.4% and 98.3% on the same vial is normal.

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u/chain_confirm_cpayments64 points·11 months ago

Yeah, the chromatogram profile matters more than the headline number.

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u/endotoxin_ellieOPmicro41 points·11 months ago

Gradient goblin mode: changed the solvent composition 17 times, finally got good resolution on a LC-MS peak.

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u/medutest_mel34 points·11 months ago

co-elution is real and gradient is usually not enough to resolve it

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u/endotoxin_ellieOPmicro21 points·11 months ago

the detector wavelength matters more than people think

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The analytical deep end: RP-HPLC methods, gradient design, integration decisions, LC-MS confirmation, amino-acid analysis, water content, and why two labs can report 98.1% and 96.4% on the same vial and both be right. Post the chromatogram, not the summary line.

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