antibacterial agent

[GS]

Sodium azide at 0.1% (1 gram per Litre) is pretty standard. It's
suppposed to be nasty - it's there to kill bugs. (It doesn't kill them
all but it stops most of them growing.) Used sensibly in small
quantities there should be no problem. If you can keep the liquid frozen
at -20 C or below, or filter through a sterilised 0.2 micron membrane
filter into a sterile vessel you may be able to dispense with a
preservative.

GS
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