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c/hplc·posted 1 months ago by u/dilara_nyberg

my A1c moved and I cannot work out whether method development is why

Question

Right, the LC-MS question again, but with numbers this time.

I have 2 data points over 16 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 am describing showed up at week 20, not week 69. People give up long before the interesting part.

Interested in whether this matches other people's logs or whether I am an outlier.

88 up / 4 down95% upvoted12 commentsid wqhhed2 Jun 2026

12 comments

12 in this archive, depth 5

best — the order this archive was captured in

u/aksel_kjaer9 points·1 months ago

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

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u/joaquin_petrov11 points·1 months ago

Did they post the raw trace or just the summary?

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u/enzo_petrescu14 points·1 months ago

a round-robin on baseline integration would be genuinely useful

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u/dilara_nybergOP8 points·1 months ago

A shoulder on the main peak that 20 analysts integrated 9 different ways. Same trace, 98.0 spread.

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u/egfr_watcher7 points·1 months ago

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

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u/dilara_nybergOP4 points·1 months ago

The Medutest result being close to my own HPLC is the signal, not the absolute number. Both are right.

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u/dilara_nybergOP2 points·1 months ago

A shoulder on the main peak that 14 analysts integrated 5 different ways. Same trace, 98.9 spread.

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u/bilal_adebayo1 point·1 months ago

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

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[removed]3 points·1 months ago

[removed by moderator]

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u/cormac_roos0 points·1 months ago

What was the column and what gradient?

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u/b12_baseline1 point·1 months ago

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

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u/runa_cabrera1 point·1 months ago

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

Yes, exactly this, and it is the bit that took me 63 weeks to accept.

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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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