How do I compare FGP and KP on lead time to the Netherlands?

For reference: FGP · KP · the Netherlands.

Both of these get recommended confidently by different people, which suggests neither is obviously right.

My constraints are cost, measurement resolution and how much handling I am prepared to do — in roughly that order.

Under what conditions does the answer flip?

Answering 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.

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.

On the detail: 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.

Price per milligram of measured peptide, not per milligram of label claim.

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.

Publish the method with the result. A comparison without the laboratory named and the submission dates given is not reproducible by anyone.

Nothing here is medical advice, and research-use compounds are not approved for human use.

Use a fixed documentation checklist rather than an impression.

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.

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 a comparison is a snapshot of the lots compared, and lots change.

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.

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.

No supplier on this site pays for its position, and the storefront links are marked nofollow and sponsored.

One laboratory, one method, one submission. Otherwise it is not a comparison.