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u/first_hundred

Member #63. The c/coa rules were my idea and I regret nothing.

long-standing contributor · joined 19 Aug 2023

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Overview — page 2 of 3

comment on help me understand LC-MS, I have read the wiki twice in c/hplc · 1 points · 6 months ago

Ran a blank after a high-concentration injection and found the carryover I had been calling an impurity.

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comment on SURPASS — 12 things I got wrong before I got it right in c/trialwatch · 119 points · 7 months ago

What was the comparator?

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comment on the STEP question that gets asked weekly, answered properly in c/trialwatch · 33 points · 7 months ago

SURPASS is the diabetes programme and reports glycaemic endpoints

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comment on the STEP question that gets asked weekly, answered properly in c/trialwatch · 5 points · 7 months ago

Read a press release and the publication three months apart. The hedging in the second one was substantial.

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comment on the STEP question that gets asked weekly, answered properly in c/trialwatch · 33 points · 7 months ago

FLOW was kidney outcomes and it is the one nobody quotes

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comment on [Lab] MKM cagri — Medutest came back 97.7% against a claimed 97.0% in c/hplc · 280 points · 7 months ago

The system suitability argument, since it comes up whenever somebody posts a number without one.

Before the sample result means anything, the instrument has to be shown to be fit that day: replicate injections with an acceptable RSD on area, a tailing factor inside limits, adequate plate count, and a resolution check between the pair you care about.

None of that is exotic and all of it is routine in a laboratory that reports for a living. Its absence does not mean a number is wrong; it means the number is unanchored, and unanchored numbers should not be quoted to two decimal places on this board.

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comment on [Discussion] we are measuring HPLC at the wrong time and calling it noise in c/hplc · 28 points · 8 months ago

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

This is the whole methodological point of the board in one line.

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comment on [Discussion] we are measuring HPLC at the wrong time and calling it noise in c/hplc · 19 points · 8 months ago

Correction: that is a tailing factor, not a plate count. Different diagnostics for different problems.

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comment on reading gradient threads from 2024 and half of it aged badly in c/hplc · 7 points · 8 months ago

a shoulder is not an impurity until you can resolve it

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comment on [Discussion] area percent is doing more work than we give it credit for in c/coa · 184 points · 8 months ago

Same view. BCH prints the column and the gradient, which means somebody could actually reproduce the run.

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comment on [Lab] 12th independent test on QST — 98.6% on a claimed 98.5%, and the trend is the interesting part in c/coa · 25 points · 9 months ago

Did you ask for the batch-specific document, or is this the catalogue one?

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comment on is it normal to get muscle cramps at week 86 in c/orforglipron · 10 points · 9 months ago

a non-peptide agonist does not degrade the way a peptide does

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comment on certificate of analysis — 18 things I got wrong before I got it right in c/coa · 61 points · 9 months ago

Left up and flaired Explainer. This is the answer we keep linking, written properly.

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comment on [Discussion] TRIUMPH is doing more work than we give it credit for in c/trialwatch · 3 points · 9 months ago

a mean is not a promise

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comment on method development — 13 things I got wrong before I got it right in c/hplc · 15 points · 10 months ago

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

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comment on [Question] how do you actually verify SURPASS in c/trialwatch · 9 points · 10 months ago

the confidence interval is the finding, the point estimate is the headline

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comment on [Meta] proposal — a flair for LC-MS posts in c/hplc · 17 points · 10 months 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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comment on [Meta] proposal — a flair for LC-MS posts in c/hplc · 409 points · 10 months 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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comment on purity — 9 things I got wrong before I got it right in c/coa · 9 points · 1 year ago

Same view. SWB prints the column and the gradient, which means somebody could actually reproduce the run.

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comment on [Question] is 97.4% actually fine or am I being sold a rounding error in c/hplc · 14 points · 1 year ago

Correction: that is a tailing factor, not a plate count. Different diagnostics for different problems.

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comment on [Question] is 97.4% actually fine or am I being sold a rounding error in c/hplc · 18 points · 1 year ago

Correcting myself upthread: I said the gradient was linear and looking again it has a hold in the middle.

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comment on [Question] is 97.4% actually fine or am I being sold a rounding error in c/hplc · 1 points · 1 year ago

Retention time shifted 0.4 minutes and I assumed the worst. It was the column temperature.

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comment on does method development actually matter or is it forum lore at this point in c/hplc · 18 points · 1 year ago

Why two honest labs report different numbers on the same vial.

Disagreeing with this bit: that spread is ordinary inter-lab variance, not a disagreement about the material.

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comment on [Question] area percent — what am I missing here in c/coa · 1 points · 1 year ago

Reminder: a question about a document is not an accusation about a supplier, and posts that blur the two get retitled.

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comment on the STEP question that gets asked weekly, answered properly in c/trialwatch · 15 points · 1 year ago

Read a press release and the publication three months apart. The hedging in the second one was substantial.

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comment on the STEP question that gets asked weekly, answered properly in c/trialwatch · 136 points · 1 year ago

Open-label extensions lose their randomisation. Anybody still enrolled at week 104 is a selected group and the numbers describe that group.

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comment on [Question] is 99.2% actually fine or am I being sold a rounding error in c/hplc · 18 points · 1 year ago

Yes. Retention time is a hypothesis about identity. Mass is the answer.

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comment on [Question] is 99.1% actually fine or am I being sold a rounding error in c/coa · 64 points · 1 year ago

Reminder: a question about a document is not an accusation about a supplier, and posts that blur the two get retitled.

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comment on [Discussion] the purity advice in here is 3 years out of date in c/coa · 128 points · 1 year ago

Left up and flaired Explainer. This is the answer we keep linking, written properly.

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comment on unpopular opinion: most of what gets said here about area percent is guesswork in c/coa · 282 points · 1 year ago

Left up and flaired Explainer. This is the answer we keep linking, written properly.

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comment on [Discussion] chromatogram is doing more work than we give it credit for in c/hplc · 21 points · 1 year ago

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

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comment on [Question] how do you actually verify SURPASS in c/trialwatch · 261 points · 1 year ago

The registered protocol is public. Comparing the registered primary endpoint with the reported one is a two-minute check and it is how outcome switching gets caught.

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comment on [Question] chromatogram — what am I missing here in c/hplc · 1 points · 1 year ago

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

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comment on why does nobody talk about SELECT in c/trialwatch · 20 points · 1 year ago

That is the 68-week readout, not the 72-week one. Different trial, different duration.

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comment on [Lab] MKM cagri — Medutest came back 97.2% against a claimed 97.0% in c/hplc · 324 points · 1 year ago

Ran a blank after a high-concentration injection and found the carryover I had been calling an impurity.

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comment on [Discussion] the COA advice in here is 2 years out of date in c/coa · 2 points · 1 year ago

Correction: that is net peptide content, not purity. Different number, different meaning, and the document says so if you read the row label.

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comment on three years of water content threads, summarised so you do not have to read them in c/coa · 460 points · 1 year ago

How to ask for a batch record without it turning into a negotiation.

Adding the bit that always gets missed: the lot on the vial has to match the lot on the page, or none of this applies to your material.

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comment on hazard ratio is the most under-discussed thing on this board in c/trialwatch · 58 points · 1 year ago

That is the 68-week readout, not the 72-week one. Different trial, different duration.

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