NOVEL SENSITIVE AND SELECTIVE METHOD FOR SPECTROPHOTOMETRIC DETERMINATION OF CERIUM(III) IN BIOLOGICAL SAMPLES USING 2,6-DIBROMO-4-CHLOROCARBOXYARSENAZO

ABSTRACT

A method is proposed for the spectrophotometric determination of trace cerium(III) in biological samples based on the reaction of Ce(III) with a new reagent, 2,6-dibromo-4-chlorocarboxyarsenazo. In 1.0 M H₃PO₄, Ce(III) reacts with 2,6-dibromo-4-chlorocarboxyarsenazo to form a 1 : 2 blue complex with an absorption maximum at 630 nm. The reaction is instantaneous and the absorbance of the complex is stable for at least 24 h at room temperature. Beer's law was obeyed for 0–0.8 µg mL⁻¹ of Ce(III). The apparent molar absorption coefficient, Sandell sensitivity, and the detection limit of the method were found to be 1.6 × 10⁵ M⁻¹ cm⁻¹, 0.876 ng cm⁻² and 2.61 ng mL⁻¹, respectively. The effect of various foreign ions on the reaction were also examined in detail, the results indicated that almost all metal ions studied can be tolerated in a considerable amounts, especially 40 mg of Zn(II), 50 mg of Mn(II), 30 mg of V(V), 100 mg of Al(III), 10 mg of Cu(II), 10 mg of Ni(II), 10 mg of Mg(II), 10 mg of Fe(III), 10 mg of Ni(II), and 12 mg of Mo(VI) didn't interfere with the determination of Ce(III), with selectivity superior to other reagents in the literature. The effect of co-existing rare earth elements on the determination of Ce(III) can be eliminated easily by a prior extraction with tri-n-butylphosphate. Proposed method is sensitive, selective, and simple, it has been successfully applied to the determination of Ce(III) in biological samples.

Keywords:

• Spectrophotometry
• Biological samples
• Ce (III)
• 2,6-Dibromo-4-chloro-carboxyarsenazo

Acknowledgments