Spectrophotometric determination of micro amounts of uranium(VI) with zephiramine

The analytical procedure is as follows. Take 25 ml of a sample solution containing (29.75178.53) μg of uranium(VI) into a 100 ml separating funnel. Add 10 ml of 2 M potassiam thiocyanate solution and 10 ml of 10-2 M zephiramine solution. The thiocyanate complex of uranium(VI) reacts with zephiramine and give a yellow precipitate. Then add exactly 10 ml of chloroform and shake for 5 minutes to extract the precipitate into chloroform. The chloroform solution has an absorption maximum at 305 nm with the molar absorptivity of 1.5×104 and is stable for at least 7 hours. The composition for the extracted species was estimated to be 1:2 (U: Zephiramine) by the continuous variation method. The calibration curve follows Beer's law in the range of 29.75 μg/25 ml to 178.53μg/25 ml in the aqueous phase. Most metal ions coexisting in the same amounts with uranium(VI) do not interfere in the determination of uranium(VI) but the small number of anions interfere.