u/first_hundred

axis labels included, always

This is an urgent-care question wearing a forum question's clothes. Please contact a clinician rather than waiting for replies.

Flair changed to match the content. Read the sidebar before posting next time and we are square.

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

Ran the same vial on two columns, different purity, both right, different separation. Method matters more than equipment.

the batch number or it did not happen

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

instrument quality is less important than analyst consistency

Sent one vial to PeptideMeter and VendorInvestigate. 93.7% and 99.1%. Cost me more than the vial did and I would do it again.

Flair changed to match the content. Read the sidebar before posting next time and we are square.

Edit to your parent would help — the concentration you quoted assumes one scenario and you have written another above it.

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

The chromatogram trace is where the real information lives. The summary number is just a headline.

[removed by moderator]

Counter-anecdote: opposite result, same dose. Which mostly tells us the variance is huge.

Retitled to remove editorialising. Put the evidence in the body.

the UK here.

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

Respectfully this is a sample of one presented as a finding.

This is the correct method framing. Column and gradient are load-bearing fields.

Slight fix: the number was 99.0, not 98.9.

Counter-anecdote: opposite result, same dose. Which mostly tells us the variance is huge.