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

small win: chromatogram stopped being a problem at week 35

Method Receipts ×1 Sourced ×2

Long-ish post, sorry. tl;dr at the bottom.

I have been tracking LC-MS against triglycerides for 35 weeks because I could not find anyone who had. The correlation is weaker than I expected, which is itself mildly interesting given how confidently people link the two in here.

Caveats up front: one person, one lab, one assay, no control, and I changed my training in the middle of it, which was stupid.

tl;dr: probably real, definitely smaller than the threads imply, and not worth reorganising your week around.

2,146 up / 361 down86% upvoted50 commentsid vmm84g9 May 2026

50 comments

29 in this archive, depth 5

best — the order this archive was captured in

u/hplc_hobbyistMOD303 points·2 months ago

Removed a chain here. The rule is one line long and it is not negotiable.

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u/honest_syringe_202581 points·2 months ago

Rodent data is rodent data. Dose scaling is not linear and the models tell you what to investigate, not what to expect.

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u/marit_mensa281 points·2 months ago

This is the correct method framing. Column and gradient are load-bearing fields.

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u/cormac_roos-32 points·2 months ago

Half-life is about 168 hours, so steady state lands around week 5–5. Practical consequence: what you feel in week 1 is not what that dose does.

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u/honest_syringe_pls1 point·2 months ago

Not to be pedantic but LC-MS and purity are being used interchangeably and they are not interchangeable in real life.

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u/dizzy_on_standing1 point·2 months ago

integration decision on a shoulder changes your number by half a point on its own

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u/andres_restrepo1 point·2 months ago

a round-robin on baseline integration would be genuinely useful

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u/reverse_image_ron1 point·2 months ago

related substances are where the story lives, not the main peak

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u/joaquin_petrov141 points·2 months ago

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

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u/naomi_antonsen200 points·2 months ago

state the method: column, gradient, detection wavelength, injection volume

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u/adaeze_batista236 points·2 months ago

the gradient is doing the separation work, not the column alone

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u/georgi_tamm68 points·2 months ago

You have restated the marketing copy. What is the actual substance here.

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u/saskia_bakker133 points·2 months ago

Rodent data is rodent data. Dose scaling is not linear and the models tell you what to investigate, not what to expect.

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u/andres_restrepo109 points·2 months ago·edited

Not to be pedantic but HPLC and purity are being used interchangeably and they are not interchangeable in real life.

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u/reverse_image_ron73 points·2 months ago

This is the correct method framing. Column and gradient are load-bearing fields.

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u/freya_baptista36 points·2 months ago

axis labels included, always

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u/week_four_wall11 points·2 months ago

state the method: column, gradient, detection wavelength, injection volume

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u/step_count_stan59 points·2 months ago·edited

The evidence standard in c/vendorvetting gets called too strict about once a month, and every time, the thread ends with the complainant agreeing.

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u/micro_bump_mick30 points·2 months ago·edited

You have restated the marketing copy. What is the actual substance here.

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u/marisol_frisk23 points·2 months ago

Mechanistically the bit that matters is chromatogram. It explains most of the early profile and a decent chunk of the outcome.

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u/samir_falk19 points·2 months ago

Mechanistically the bit that matters is chromatogram.

Counter-anecdote: opposite result, same dose. Which mostly tells us the variance is huge.

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u/dilara_nyberg0 points·2 months ago

chromatogram or it did not happen

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[removed]13 points·2 months ago

[removed by moderator]

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u/rina_nascimento44 points·2 months ago

You have restated the marketing copy.

Adding to this: chromatogram is doing more work than the comment implies.

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u/rasmus_petrescu19 points·2 months ago

Titration speed is a side-effect dial far more than an efficacy dial.

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u/honest_syringe_pls12 points·2 months ago

the detector wavelength matters more than people think

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u/santiago_villalobos7 points·2 months ago

two labs, two different baselines, two different purity numbers, both honest

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u/step_count_stan3 points·2 months ago

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

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u/week_four_wall4 points·2 months ago

Did they post the raw trace or just the summary?

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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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