What I have: MKM · Qingdao Saber Technology.
The comparison I want does not seem to exist anywhere in a form I can evaluate.
I have read the arguments for each and they do not engage with each other.
What does each option buy me, and what does it cost me?
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.
| Step | Value | Note |
|---|---|---|
| Vial price, 10 mg nominal | £34.00 | As advertised |
| Nominal cost per mg | £3.40 | 34 ÷ 10 |
| Measured content | 9.2 mg | Independent content assay |
| Cost per actual mg | £3.70 | 34 ÷ 9.2 |
| Dead-space loss, 20 draws | 4 % | 80 µL of a 2 mL fill |
| Cost per delivered mg | £3.85 | 3.70 ÷ 0.96 |
| First vial, with £110 assay | £14.85 | Testing dominates a single vial |
The part that matters: lead time and lane behaviour are supplier properties too and are easier to compare than analytical ones, because they need no laboratory at all.
Content assay results across the published datasets vary considerably more between suppliers than purity does, which makes content the more discriminating axis.
The caveat is that a comparison is a snapshot of the lots compared, and lots change.
One laboratory, one method, one submission. Otherwise it is not a comparison.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe relevant point is that two competent laboratories disagree by half a per cent on identical material, which is larger than most of the differences people argue about.
Sample size matters. One order each is an anecdote about six vials; three orders each over a year is the beginning of a comparison.
Worth being precise here: cost per milligram of actual peptide is the honest price comparison, which means dividing by measured content rather than by label claim.
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.
Comparisons drawn from different laboratories at different times are weaker evidence than most people treat them as.
Price per milligram of measured peptide, not per milligram of label claim.
Worth being precise 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.
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.
Nothing here is medical advice, and research-use compounds are not approved for human use.
Use a fixed documentation checklist rather than an impression.
edited 26 Aug 2025 by tobias_maartens — added a caveat about sampling
A single member running three suppliers on one method is worth more than thirty members running one supplier each.
Content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.
Compare content, not purity. Purity clusters and content does not.
Put another way, ratings on this site are ours alone and are deliberately not reconciled with anyone else's.
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.
No supplier on this site pays for its position, and the storefront links are marked nofollow and sponsored.
Name the laboratory and the dates or the comparison cannot be reproduced.
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.