Details up front: JEEP · Shanghai ERP Biotechnology.
I want to know what the trade-off actually is rather than which option is fashionable.
I would rather have a defensible reason than a marginal improvement.
Which axes does this decision turn on?
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.
Cost per milligram of actual peptide is the honest price comparison, which means dividing by measured content rather than by label claim.
| 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 relevant detail is that 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.
The caveat is that a comparison is a snapshot of the lots compared, and lots change.
Name the laboratory and the dates or the comparison cannot be reproduced.
edited 28 Jul 2026 by tobias_maartens — corrected a unit error in the worked example
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe short version: same compound, same laboratory, same method, ideally same week — otherwise you are comparing laboratories rather than suppliers.
Sample size matters. One order each is an anecdote about six vials; three orders each over a year is the beginning of a comparison.
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.
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.
No supplier on this site pays for its position, and the storefront links are marked nofollow and sponsored.
Price per milligram of measured peptide, not per milligram of label claim.
Start by asking what you are optimising for, because cost per milligram, documentation depth and lead time do not have a common winner.
Content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.
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.
Content assay results across the published datasets vary considerably more between suppliers than purity does, which makes content the more discriminating axis.
Comparisons drawn from different laboratories at different times are weaker evidence than most people treat them as.
Compare content, not purity. Purity clusters and content does not.
More usefully, ratings on this site are ours alone and are deliberately not reconciled with anyone else's.
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.
Nothing here is medical advice, and research-use compounds are not approved for human use.
Use a fixed documentation checklist rather than an impression.
The 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.
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.
The caveat is that none of this makes an unapproved product safe or lawful to use. It reduces one category of uncertainty — what is in the vial — and leaves every other category untouched.
One laboratory, one method, one submission. Otherwise it is not a comparison.
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.