Sounds like you've being using it for a while; so what do you see in the bottom of the dewar?

If you looking at a relatively small dewar, say 2 liters, 2 ppm volume is 0.004 cc's of water.  

I don't think you can distiguish that amount from the amount of condensation from the air.  Additionally, most labs run on the dry side for RH, so it would evaporate relatively quickly in any case.

TTFN

You have to purge the tank or the container every month or two months one to make sure that you will not have any acunolate resdue in the bottom of the tank 2ppm is nothing in the Nitrogen and it will evaporate with gas.

regards

Unless you let your storage system (dewar or ?) come up to ambient temperature, the "water" will stay suspended as ice floating around in the LN2.  Even if you drain your dewar, it will stay below the freezing point of water for quite a while.  The ice particals are probably so small they won't be a problem with the "industrial" spec you are more than likely being delivered.,  If this is not acceptable, ask for a better specification and be prepared to pay for it!   If you are using liquid for cooling or ? you will probably never see it.  If you are using the nitrogen as a gas, when the liquid is vaporized and brought up to ambient the water will eventuall be brought out with it (they test it in the vapor phase).  

Good luck!

I go by IRstuff telling u that 2 PPM moisture in LN is nothing but 0.0002% of Nitrogen at ambient pressure. When placed in dewar, a slight increase in tempe will make niterogen boi more and the concentration of moisture will rather reduce by 0.005% at ambient pressure.

hei, NO SYSTEM IS 100% EFFICIENT..

RC