Facile spectrophotometric determination of Cd(II) and Pb(II) using murexide reagent in mixed solvent system

Khaled Muftah Elsherif, Zainab Y. Alzalouk, Ahmed Zubi and Salima Al-Seddik Al-Ddarwish

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The spectrophotometer method was employed to determine the trace level of hazardous elements (cadmium and lead). Murexide interacts with Cd(II) and Pb(II) in slightly acidic and basic solutions (pH 3-9) to form orange to reddish orange chelates with absorbance maxima at 483 and 504 nm. The reaction is rapid, and the absorbance remained constant for more than three hours. The average molar absorptivity and sensitivity values for Cd and Pb were determined to be (11856 L.mol-1.cm-1 and 0.107 ppm-1) and (2422 L.mol-1.cm-1 and 0.061 ppm-1), respectively. Linear calibration curves for 0.5-7.0 mg.L-1 Cd and 0.75-12.0 ppm Pb were produced. The chelate's stoichiometric composition was 1:2 (metal ion: murexide) except for Pb in the 6:4 proportion, which had a 1:1 mole ratio. Moderate levels of some interfering ions have no effect on the determination of Pb(II) and Cd(II) ions.