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c/hplc·submitted 1 year ago by u/adaeze_batista

tried method development for 12 weeks. here is what happened.

Questionbranch of 13 comments

Right, the method development question again, but with numbers this time. I have 15 data points over 32 weeks. The pattern is consistent enough that I do not think it is chance, and boring enough that nobody is going to screenshot it, which is usually a good sign. The thing I would flag for anyone new: the effect I…

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13 comments, started 1 year ago
u/teodor_szabo-7 points·1 year ago

Water content matters more than people think. If a vial is carrying residual moisture, your "10mg" is not 10mg of peptide.

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u/adaeze_batistaOP-8 points·1 year ago

Half-life is about 168 hours, so steady state lands around week 6–5. Practical consequence: what you feel in week 1 is not what that dose does.

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u/erez_yilmaz1 point·1 year ago

axis labels included, always

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[deleted]1 point·1 year ago

[deleted]

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u/cormac_roos1 point·1 year ago

Strongly agree. Largest single impurity tells a different story than total purity.

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u/nnt_nate1 point·1 year ago

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

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u/nora_lundgren1 point·1 year ago

Half-life is about 168 hours, so steady state lands around week 6–5.

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

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u/georgi_chowdhury1 point·1 year ago

What was the column and what gradient?

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u/adaeze_batistaOP0 points·1 year ago

Edit to your parent would help — the concentration you quoted assumes one scenario and you have written another above it.

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u/adaeze_batistaOP1 point·1 year ago

A shoulder on the main peak that 6 analysts integrated 15 different ways. Same trace, 96.2 spread.

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u/santiago_villalobos1 point·1 year ago

area% and mass% are not the same and this whole post conflates them

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u/hamza_weiss1 point·1 year ago

A shoulder on the main peak that 6 analysts integrated 15 different ways.

Yes, exactly this, and it is the bit that took me 14 weeks to accept.

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u/bilal_adebayo1 point·1 year ago

Strongly agree. Largest single impurity tells a different story than total purity.

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