Determination of uranium in technological waters by ion-pair liquid chromatography

U(VI) can be efficiently determined in the range 0.3-1OmM after its separation from Th(IV), Zr(IV), Al(III), Fe(III), lanthanides and other ions by ion-pair liquid chromatography on a 3 x 150 mm glass column packed with Separon SGX C18 modified with sorbed ammonium dodecyl sulphate. Traces of uranium can be preconcentrated directly on the analytical column from acidified water solutions and separated from Th, Zr, Al, Fe, lanthanides and other elements, with an enrichment factor of $ 100 and recovery of 98 +/- 8%, by isocratic or pH or concentration gradient elution with ammonium 2-hydroxy-2-methylpropionate or ammonium citrate solution. Post-column derivatization with 25muM Arsenazo III in 0.1M formate buffer at pH 2.7 is used for detection and quantification.