What should I ask a supplier before ordering that they cannot fake?

I would rather spend on verification than on volume.

This is a procedural question rather than a theoretical one, and I would like the procedure rather than the theory.

What I have done so far is read the label documentation where it exists and the two pharmacopoeial monographs that are publicly available, which cover the licensed presentation and say nothing about a research one.

What is the correct sequence, and where is the step that people usually skip?

The honest answer is that a small first order tested independently beats any amount of reading, and it costs less than most people expect.

The single most informative free test is asking for the certificate of the lot they intend to ship and then confirming, on arrival, that the code on the glass matches it. A supplier who can do that has a traceability system; one who cannot does not.

Put another way, published third-party data on a named lot is worth more than any aggregate rating, because it is about a specific object rather than about an average of other people's objects.

Purity by RP-HPLC and quantified content are separate measurements answering separate questions, and only the second one tells you how many milligrams are in the vial.

Small first order, independent submission, then scale. In that order.

edited 17 Mar 2026 by ilaria_bertone — expanded the table to cover the lower concentration

The short version: ask for the lot-specific certificate, check the method section, check the lot code ties to a vial, then spend a small amount and test it yourself.

The pre-order sequence: request a lot-specific certificate for the exact line, check that it names a lot code rather than a batch family, check that it carries the column, gradient and detection wavelength, and check the analysis date is recent relative to the lot.

The post-arrival sequence: inspect before reconstitution, photograph anything unexpected, confirm the lot code is physically on the vial, and submit a sample to an independent laboratory before committing to a larger order.

Match the code on the glass to the code on the certificate. Everything else is secondary.

Answering this needs to know whether you have already ordered, because the pre-order checks and the post-arrival checks are different lists.

Independent submission costs a fraction of a mid-sized order at any of the services this community uses, and it converts an opinion into a number attached to your own material.

Set your accept threshold before you see the result. Deciding after the number arrives is how thresholds become negotiable, and everybody does it unless they wrote it down first.

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

Write your accept threshold down before the result arrives.

Answer first: vet the documentation before you vet the supplier, because documentation is the only thing you can assess before spending anything.

Repeat the exercise on a second lot months later. Lot-to-lot agreement is the property that actually predicts your next order, and it cannot be established from one submission.

The caveat is that a good result on one lot is a fact about that lot. It is a prior for the next one, not a guarantee.

Two lots agreeing is worth more than one lot excelling.

Reputation is a prior. An independent result on your own vial is the evidence.

Ask what happens if a result comes back outside specification. The answer is informative regardless of what it is, and the question itself tells you something about how it lands.

Ask for the lot-specific certificate before ordering. It is free and it is decisive.