[Discussion] can we stop arguing about related substances until somebody posts a number
I have had 17 orders now and I keep a table, so here is the honest summary rather than a vibe.
Material has been consistent. Communication has not. Shipping has varied by about 4 days on nominally the same lane, which matters more in summer than in February.
The independent number came back 96.8% against a claimed 99.1%, which I read as agreement rather than a discrepancy — inter-lab variance on this assay is a point or two either way and treating one lab as ground truth is how people end up in pointless arguments with vendors.
Batch number is in the comments. Ask if you want the method.
best — the order this archive was captured in
redact your own name, not the vendor's batch details
redact your own name, not the vendor's batch details
Disagree on that part. 95.1% and 98.7% on the same vial is normal.
redact your own name, not the vendor's batch details
Yes, exactly this, and it is the bit that took me 87 weeks to accept.
the related substances line is where the story is
purity and net content are two different numbers, same vial
purity and net content are two different numbers, same vial
Disagree on that part. 97.4% and 97.6% on the same vial is normal.
That is net peptide content, not purity. Different number, different meaning.
the counterion is part of the mass you paid for
Inter-lab variance on this kind of assay is routinely 1–2 points. Different column, different gradient, different integration.
Sceptical. If this were true we would see it reflected in the data and we do not.
Tested the GLB raw material and a reseller vial side-by-side. Same purity claim, different impurity profiles. Handling matters.
Water content on the document? That affects your concentration math.
Four months on the site and I was confusing area% and mass% in every post I made. One explainer thread and it clicked.
area% is not mass%, and here is exactly why it matters
Every time this gets posted it hits the front page and every time someone has to re-explain it.
Water content was 3.8%, acetate was 6.2%, purity was 99%, but net peptide was only 90% of the label weight. Perfectly honest, just chemistry.
axis labels included, always
Water content on the document? That affects your concentration math.
Sent one vial to PeptideMeter and VendorInvestigate. 96.8% and 99.1%. Cost me more than the vial did and I would do it again.
Edit to your parent would help — the concentration you quoted assumes one scenario and you have written another above it.
axis labels included, always
PDF metadata is checkable in fifteen seconds
- 1redact your own name, not the vendor's batch details9 comments in this branch · started by u/halima_boateng
- 2Every time this gets posted it hits the front page and every time someone…8 comments in this branch · started by u/sig_figs_sam