The original plastic containers (at least, the ones I've received from Fuji) are HDPE, which is quite impermeable. The oxygen dissolved in the water that the concentrates are made up in is far greater than the oxygen that can diffuse through the container.
Originally Posted by AgX
Anything that someone does at home is going to ruin the nitrogen filling and run far greater risks than just leaving the chemicals in the manufacturer's containers.
Once you've opened the containers of course, by all means transfer stuff to glass bottles etc. The concentrate containers often don't seem to seal very well once the thermal seal is broken.