How do I compare TFC and GL Biochem on lead time to Singapore?

The specifics, since they change the answer: TFC · GL Biochem · Singapore.

These are treated as interchangeable and I do not think they are.

If both are acceptable I would like to know that, so I can stop thinking about it.

Is there a defensible reason to prefer one, or is this a coin flip?

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

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.

Cost per milligram of actual peptide is the honest price comparison, which means dividing by measured content rather than by label claim.

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

Use a fixed documentation checklist rather than an impression.

Ratings on this site are ours alone and are deliberately not reconciled with anyone else's.

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 be exact about it, sample size matters. One order each is an anecdote about six vials; three orders each over a year is the beginning of a 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.

The relevant detail is that this is the question where methodology matters more than the conclusion.

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.

It helps to be literal here: content is the more discriminating measurement than purity for supplier comparison, because purity clusters tightly among competent suppliers and content does not.

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.

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

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

edited 15 Mar 2025 by b_delacroix — added the method parameters

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.

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.

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