How do I compare CPC and GGPeps on lead time to Ireland?

The specifics, since they change the answer: CPC · GGPeps · Ireland.

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?

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.

Content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.

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

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.

edited 16 Sept 2025 by forty_two_c — fixed an arithmetic slip in the third paragraph

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.

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.

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.

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.

Put another way, this is the question where methodology matters more than the conclusion.

Lead time and lane behaviour are supplier properties too and are easier to compare than analytical ones, because they need no laboratory at all.

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.

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.

Compare content, not purity. Purity clusters and content does not.