Research chems - Igf-1, Ghrp2&6, Thymosin b4 - how sterile are they?

I was wondering this. .

Considering most peptides including the ones mentioned in the title are "research" chems how can we strust the sterility of them?

For instance, if you were to buy directly off a research company who advocates that their chemicals are for research purposes only, how can you be sure that they are clean?

Or would you say they must they be sterile even for research purposes as it should be considered best practice.

Gotta know and trust your source.

Yeah I would Imagine it comes down to who your using and what their reputation has been