How Many Vials Needed for Testing?

tl;dr: just one.

Number of vials required for testing

In principle, you only need to send one vial of your sample to conduct multiple tests, beyond the basic identity, purity, and quantity (potency) test: endotoxins, heavy metals (FDA4), and solvents can be screened on the same sample.

Our partner lab for many of those tests, Krause Analytical, follows a process that's suitable to screen for those contaminations on the same sample vial.

Depends on the lab

However, not all labs follow the same process, and some prefer to perform different tests on separate samples.

If you select BTLabs as your "lab choice", and also select an endotoxins test, you have the option of sending two vials, which the lab prefers to give a solid reading.

Indeed, BTLabs opens the vial for the standard test, in order to weigh the powder. This step does not work well with subsequent endotoxins screening.

In that case, you must absolutely ensure that both samples come from the same batch.