Sodium fluoride can be used to make Sarin, but considering that you can obtain a suitable fluoride from just about any fluoride salt it doesn’t seem like monitoring this particular compound is a useful measure for controlling the spread of chemical weapons. Which is why it’s not a precursor under the chemical weapons convention. Now, something like http://en.wikipedia.org/wiki/Methyl_phosphonic_dichloride … that you’d want to monitor.
