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Single comment threadYou are looking at one branch of [Lab] KP cagri — VendorInvestigate came back 98.1% against a claimed 97.5% — 53 comments in the full submission. View in context.
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c/hplc·submitted 2 years ago by u/week_four_wall

[Lab] KP cagri — VendorInvestigate came back 98.1% against a claimed 97.5%

Labbranch of 14 comments

Title says it — KP cagri — VendorInvestigate came back 98.1% against a claimed 97.5% — so here is the boring supporting detail that makes it worth anything. 98.1% and 97.5% — those are the numbers, and they are the ones I am willing to defend. A shoulder that does not baseline-resolve cannot be quantified honestly.…

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14 comments, started 2 years ago
u/aksel_palacios110 points·2 years ago

That figure cannot be quoted to two decimals off that baseline. The precision is not in the data.

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u/hazard_ratio_halstats29 points·2 years ago

Same view — reporting the gradient is what makes a result checkable rather than merely stated.

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u/erez_yilmaz8 points·2 years ago

Area percent is the integrated area of your peak over the total integrated area at one wavelength on one gradient. Change any of those and the number changes without the sample changing.

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u/blunt_coldbox_20243 points·2 years ago

Cosigning the wavelength point. Half the disagreements in this board are two people looking at different detectors.

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u/peak_area_peteMOD63 points·2 years ago

Left up. The integration disagreement in this thread is the most useful thing on the board this week.

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u/rosa_sandvik22 points·2 years ago

Agreed, and it is why SWB printing the column and gradient on the certificate is genuinely useful rather than decorative.

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u/dead_space_doug15 points·2 years ago

Gave the same trace to two people I trust and got two integrations about a point apart. That was the most educational afternoon I have had here.

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u/egfr_watcher11 points·2 years ago

report the method or do not report the number

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u/camila_lindqvist9 points·2 years ago

How old is the column and roughly how many injections has it seen?

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u/georgi_chowdhury16 points·2 years ago

the column has a history and it shows in the peak shape

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u/fatima_yildiz5 points·2 years ago

integration decisions move the number more than the sample does

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u/teodor_szabo129 points·2 years ago

system suitability before you believe any number on the run

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[deleted]55 points·2 years ago

[deleted]

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u/phase_two_pete73 points·2 years ago

Small fix — 214nm, not 210. It matters for the comparison you are making with the other run.

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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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