Multisyringe flow injection analysis for the spectrophotometric determination of uranium (VI) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

The spectrophotometric determination of uranium (VI) has been developed using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP). This reaction has been adapted to apply a multisyringe flow injection analysis (MSFIA) system with spectrophotometric detection. The ternary complex of uranium (VI)-(Br-PADAP)-F has been measured at 578 nm. The procedure was optimized using univariate method and two-level full factorial. Four variables (concentrations of Br-PADAP, CyDTA, NaF and sample volume) were regarded as factors in the extraction optimization. Results of the two-level full factorial design, showed that only two factors (concentration of Br-PADAP and CyDTA) are statistically significant. The calibration curve is linear over the range 0.3–5 mg L−1 uranium (VI) with a relative standard deviation of 4.0% (1 mg L−1 uranium (VI), n = 10). The recoveries of uranium in water samples were between 80 and 102%.