The particulars: GGPeps · Tianjin Finder Chemical.
I am trying to choose between two options that are usually discussed as though only one exists.
I am not optimising for price, but I am not indifferent to it either.
Which axes does this decision turn on?
Ratings on this site are ours alone and are deliberately not reconciled with anyone else's.
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 |
Sample size matters. One order each is an anecdote about six vials; three orders each over a year is the beginning of a comparison.
Content assay results across the published datasets vary considerably more between suppliers than purity does, which makes content the more discriminating axis.
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 resultsAnswering this needs the axis. A supplier that is best on paperwork and a supplier that is best on price are both correct answers to different questions.
Content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.
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.
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.
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.
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.
Use a fixed documentation checklist rather than an impression.
edited 21 Dec 2025 by deamidation_watch — clarified the distinction between purity and content
Start by asking what you are optimising for, because cost per milligram, documentation depth and lead time do not have a common winner.
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.
Compare content, not purity. Purity clusters and content does not.
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.