How does FGP compare to GL Biochem (Shanghai) on documentation quality?

Details up front: FGP · GL Biochem (Shanghai).

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.

What is the actual trade-off, and does it matter at the scale I am working at?

Start by asking what you are optimising for, because cost per milligram, documentation depth and lead time do not have a common winner.

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

Mechanically, 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.

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

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.

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.

The part that matters: 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.

Use a fixed documentation checklist rather than an impression.

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.

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.

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.

Worth being precise here: a single member running three suppliers on one method is worth more than thirty members running one supplier each.

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.

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