How do I compare QST and MKM on lead time to Poland?

Setup, so nobody has to ask: QST · MKM · Poland.

I would like the axes of comparison first and the recommendation second.

I have tried the first option and it works; the question is whether the second is better rather than merely different.

Under what conditions does the answer flip?

Worth being precise here: ratings on this site are ours alone and are deliberately not reconciled with anyone else's.

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.

Sample size matters. One order each is an anecdote about six vials; three orders each over a year is the beginning of a comparison.

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.

Name the laboratory and the dates or the comparison cannot be reproduced.

A single member running three suppliers on one method is worth more than thirty members running one supplier each.

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.

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.

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.

The short version: same compound, same laboratory, same method, ideally same week — otherwise you are comparing laboratories rather than suppliers.

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.

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.

edited 14 Sept 2025 by greta_holzmann — removed a claim I could not source

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.

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.