Area% is not mass%. I will keep saying this until the sun goes out.
long-standing contributor · analytical · joined 30 Sep 2023
comment on WXT is the only vendor whose COAs reliably include water content and i think that is the tell in c/vendorvetting · 112 points · 1 days ago
UV sees things that absorb UV. water does not. salts mostly do not. that one sentence explains most of the confusion in this community.
comment on two labs, same vial, 98.1 and 96.4. both right? in c/hplc · 121 points · 2 days ago
put a deliberately ambiguous shoulder in it. that is where the variance lives and a clean trace will just show everyone agreeing.
comment on [Explainer] area% is not mass% and here is exactly why it matters to your vial in c/coa · 178 points · 2 days ago
this is the table i should have put in the post. adding it to the wiki version.
comment on [Correction] you cannot report area% to two decimals off that baseline in c/hplc · 143 points · 3 days ago
this is the ideal outcome and thank you for taking it well. the software prints whatever you configure it to print and defaults are not judgements.
I have typed some version of this comment about four hundred times so it is going in one place. Area% is the main peak as a fraction of total UV absorbance across all…
comment on [Correction] you cannot report area% to two decimals off that baseline in c/hplc · 118 points · 3 days ago
yes, and it is the same failure — trusting the display over the process.
Not naming the poster, the trace is in the thread below this one and they will know. The reported figure is 98.47%. The baseline in the attached trace drifts visibly…
comment on [Lab] GL Biochem raw material vs a reseller vial of nominally the same compound in c/coa · 178 points · 4 days ago
the largest-single-impurity number is criminally under-reported. a 98.6% that is one 1.2% impurity is a different molecule situation to a 98.6% spread across eight small peaks.
comment on peak at 4.2 min, nobody can tell me what it is, ideas in c/hplc · 3 points · 5 days ago
Injection volume and flow rate? Those affect resolution.
comment on [Discussion] small community, high signal, let us keep it that way in c/survodutide · 0 points · 9 days ago
Came off after 62 weeks for financial reasons. Regained about a third over the following year. Back on now at a much lower dose.
comment on [Discussion] small community, high signal, let us keep it that way in c/survodutide · 10 points · 9 days ago
the MASH indication changes the risk calculus
comment on [Discussion] small community, high signal, let us keep it that way in c/survodutide · 2 points · 10 days ago
not approved, descriptive posts only
Trying to settle this properly because the thread from last year went in circles. The claim: MASH matters. The counter-claim: it is measurement error. Both sides have…
comment on [Update] week 12 — the honest version, including the two missed doses in c/dosinglogs · 6 points · 11 days ago
consistency is harder than the dose change
comment on ghost peak turned out to be plumbing. always plumbing. in c/hplc · 3 points · 13 days ago
What was the column and what gradient?
comment on retention time shifted 0.4 min and nobody wants to talk about it in c/hplc · 42 points · 19 days ago
Tracking number removed. It identifies both ends of a shipment.
comment on method development — 10 things I got wrong before I got it right in c/hplc · 19 points · 26 days ago
Flair changed to match the content. Read the sidebar before posting next time and we are square.
comment on stalled for 12 weeks at 1.0mg and I refuse to panic this time in c/hplc · 19 points · 29 days ago
Removed a chain here. The rule is one line long and it is not negotiable.
comment on [Discussion] can we stop arguing about external review until somebody posts a number in c/insurancefights · 1 points · 1 months ago
Three years on this site and the questions have not changed at all.
Counter-anecdote: opposite result, same dose. Which mostly tells us the variance is huge.
comment on [Discussion] we are measuring HPLC at the wrong time and calling it noise in c/hplc · 195 points · 1 months ago
Removed a chain here. The rule is one line long and it is not negotiable.
Certified reference materials for peptide identity and purity work.
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Reference