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c/hplc·submitted 8 months ago by u/rasmus_kimani

[Lab] 24th independent test on QSC, and the trend is the interesting part

Labbranch of 12 comments

gradient. That is the whole post, but I will justify it. Everything else people worry about in c/dosinglogs is downstream of it. Titration speed, reflux, the endless dose arguments — most of it resolves if you sort gradient out first, and almost nobody does. I say this having got it wrong for 14 months. My ApoB was…

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12 comments, started 8 months ago
u/b12_baseline264 points·8 months ago
i do not know. that is the honest answer.
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u/ewan_marchand79 points·8 months ago·edited

Dead space in the needle hub holds a small but non-trivial volume. On low-volume draws that can be several units.

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u/egfr_watcher48 points·8 months ago

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

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[deleted]116 points·8 months ago

[deleted]

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u/egfr_watcher170 points·8 months ago

i do not know.

Disagree on that part. 98.1% and 97.6% on the same vial is normal.

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u/gustav_solberg88 points·8 months ago

i do not know.

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

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u/hana_lehtinen25 points·8 months ago

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

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u/liv_okafor91 points·8 months ago

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

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u/rosa_sandvik99 points·8 months ago

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

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u/lina_novak48 points·8 months ago

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

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u/yara_boateng28 points·8 months ago

Small correction: the trial was 20 weeks, not 36. Does not change your point but people will quote it.

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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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