Spectrophotometic determination of barium in Si-Al-Ba alloy with chlorophosphonazo III

The color reaction of reagent chlorophosphonazo Ⅲ with barium was studied.In a medium of NH3.H2O-NH4Cl at pH10,barium reacts with the reagent to form a green complex which exhibits an absorption maximum at 670 nm with a apparent molar absorptivity of 6.49×104 L mol-1 cm-1.Beer's law is obeyed in the range of 0-50 μg/25 mL for barium.The effect of aluminium and iron on the determination of barium can be overcome by complexing them with triethanolamine and 1,10-phenanthroline.Interference from calcium can be eliminated by using potassium fluoroborate.The proposed method has been applied to the determination of barium in Si-Al-Ba alloy with the RSD(n=5)of less than 2%.The determination results are agreement with the certified values.