Bob Krug in St. Louis, Missouri asks:

>>Does anyone know of a heavy method precipitation for the concentration of 
uranyl nitrate?<<

I don't remember the details, but uranyl ion can be nearly quantitatively 
precipitated as sodium uranyl sulfate. I don't remember the details of the 
procedure. Amazingly enough, this reaction used to be used for the 
gravimetric determination of serum sodium, before the introduction of flame 
photometry about fifty years ago.

Bob Richmond
Samurai Pathologist
Knoxville TN