What I have: SSA · 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?
The honest answer is that most claimed differences between reputable suppliers are inside inter-laboratory noise.
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 |
More usefully, content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.
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.
HPLC purity, identity confirmation and quantified content on the vial you actually hold. Reports arrive with the chromatogram attached, not just a number.
Submit a sampleFounded 1998. ISO 9001 and cGMP certified, 1,500+ staff and 200+ patents. The synthesis house behind a great many of the vials that get sent out for testing - batch-specific documentation with every order.
Visit GL BiochemThe short version: same compound, same laboratory, same method, ideally same week — otherwise you are comparing laboratories rather than suppliers.
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.
It helps to be literal here: 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.
Use a fixed documentation checklist rather than an impression.
Mechanically, this is the question where methodology matters more than the conclusion.
Sample size matters. One order each is an anecdote about six vials; three orders each over a year is the beginning of a comparison.
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.
One laboratory, one method, one submission. Otherwise it is not a comparison.
edited 9 Aug 2024 by micron22 — added the method parameters
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.
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.
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.
Publish the method with the result. A comparison without the laboratory named and the submission dates given is not reproducible by anyone.
The published aggregate datasets from Janoshik, Medutest and PeptideMeter are the closest thing to a systematic evidence base in this space, and the striking pattern across all three is that identity is almost always confirmed, purity is usually acceptable, and content is where the variance lives.
Comparisons drawn from different laboratories at different times are weaker evidence than most people treat them as.
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.