determination of uranium in natural water and complex solutions using ion exchange chromatography: a combined procedure using ion exchange chromatography and uv-vis spectrophotometry techniques has been developed to measure uranum in natural water and complex solutions. after conditicing , one hundred milli liters of sample solutions have been passed through an ion exchange column,pachked with amberlite ira-904 resin, where uranium is concentrated and separated from the bulk of the other constituents.then the amount of uranium in natural water)trace level(and in complex soluticos are monitored spectrophotometricaly with the chromogenic reagents rhodamine - b and 2-)4-pyridylazo(- resorcinol , respectively. analysis of simulated different samples have shown that the procedure is free from major interferences such as fe3+ , v5+ , mo6+ and etc. it has been found that the detection limit for chromogenic reagent rhodamine - b with ion exchange chromatography separation procedure is less than ng.m1-1 , and recoveries of uranium by ion exchange chromatography are in the 98-99.9 range.