Ampicillin

[Wen Huang]

Hi,

I was wondering what kind of ampicillin should I use to make LB-amp+  
media and LB-agar plates

I searched the internet and there are three versions of amplicillins

1. ampicillin
2. ampicillin sodium salt
3. ampicillin trihydrate

I am pretty sure people use ampicillin sodium salt for cell culture,  
just want to make sure that what I should use for bacteria culture.

By the way, when these things go into water, do they have the same  
activity?

Thanks,
Wen