Stated plainly: TFC · Zhuhai Kerui Biotechnology.
These are treated as interchangeable and I do not think they are.
If both are acceptable I would like to know that, so I can stop thinking about it.
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.
Cost per milligram of actual peptide is the honest price comparison, which means dividing by measured content rather than by label claim.
Put another way, content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.
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.
Compare content, not purity. Purity clusters and content does not.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsIt helps to be literal here: this is the question where methodology matters more than the conclusion.
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.
The relevant detail is that lead time and lane behaviour are supplier properties too and are easier to compare than analytical ones, because they need no laboratory at all.
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.
Name the laboratory and the dates or the comparison cannot be reproduced.
On the detail: 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.
Put another way, sample size matters. One order each is an anecdote about six vials; three orders each over a year is the beginning of a comparison.
Comparisons drawn from different laboratories at different times are weaker evidence than most people treat them as.
One laboratory, one method, one submission. Otherwise it is not a comparison.
edited 5 Jun 2026 by j_wierzbicki — expanded the table to cover the lower concentration
Put another way, a single member running three suppliers on one method is worth more than thirty members running one supplier each.
Publish the method with the result. A comparison without the laboratory named and the submission dates given is not reproducible by anyone.
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.
Price per milligram of measured peptide, not per milligram of label claim.
Answer first: comparing suppliers is only meaningful if the comparison holds the laboratory, the method and the compound constant, and most published comparisons hold none of them.
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.
No supplier on this site pays for its position, and the storefront links are marked nofollow and sponsored.
Use a fixed documentation checklist rather than an impression.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.