Determination of micro amount of bismuth in Al alloys by spectrophotometry

A sensitive method for the determination of Bi by spectrophotomctry was developed.Chlorophosphonazo Ⅲ can react with bismuth to form a stable red complex.The results showed that the maximum absorption of the complex is at 510 nm,the molar absorptivity is 1.567×105 L·mol-1·cm-1.Beer′s law was obeyed in the range of 0～0.60 μg/mL.The method was applied to direct determination of Bi in Al alloys and satisfactory results were achieved.