Is BCH worth the price difference against Xi’an Mokemei Biotechnology on measured results?

Concretely: BCH · Xi’an Mokemei Biotechnology.

Both of these get recommended confidently by different people, which suggests neither is obviously right.

My constraints are cost, measurement resolution and how much handling I am prepared to do — in roughly that order.

Is there a defensible reason to prefer one, or is this a coin flip?

Start by asking what you are optimising for, because cost per milligram, documentation depth and lead time do not have a common winner.

Publish the method with the result. A comparison without the laboratory named and the submission dates given is not reproducible by anyone.

Compare documentation on a fixed checklist rather than by impression: lot specificity, method section, chromatogram availability, quantified content, water and counter-ion figures, and whether the code is on the vial.

Gradient slope, column chemistry and detection wavelength all affect the reported purity figure, which is why the method section is the part that makes results comparable.

Name the laboratory and the dates or the comparison cannot be reproduced.

The short version: same compound, same laboratory, same method, ideally same week — otherwise you are comparing laboratories rather than suppliers.

To compare properly: order the same compound at the same nominal strength from each supplier, submit all samples to the same laboratory in the same submission if possible, and ask for the same test set on each.

On the detail: content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.

The ratings on this site are a community opinion average on a ten-point scale and are not reconciled with any other community's figures.

Use a fixed documentation checklist rather than an impression.

Ratings on this site are ours alone and are deliberately not reconciled with anyone else's.

Submitting to different laboratories introduces a method difference that commonly exceeds the supplier difference. Gradient slope alone can move a reported purity figure by a per cent in either direction.

Cost per milligram of actual peptide is the honest price comparison, which means dividing by measured content rather than by label claim.

Content assay results across the published datasets vary considerably more between suppliers than purity does, which makes content the more discriminating axis.

Price per milligram of measured peptide, not per milligram of label claim.

edited 16 Sept 2024 by petra_hovland — added the method parameters

This is the question where methodology matters more than the conclusion.

Lead time and lane behaviour are supplier properties too and are easier to compare than analytical ones, because they need no laboratory at all.

Inter-laboratory spread on identical peptide material is routinely half a per cent to a per cent by RP-HPLC, which is the noise floor for any cross-laboratory comparison.

No supplier on this site pays for its position, and the storefront links are marked nofollow and sponsored.

One laboratory, one method, one submission. Otherwise it is not a comparison.