A facile, highly sensitive, and selective spectrophotometric method has been developed
for the determination of aluminum and copper in different alloys. The method is based
on the formation of the binary complexes of aluminum and copper with Alizarin yellow
R (AYR) [5-(4-nitrophenylazo) salicylic acid] at pH 2.0 and 6.2, respectively, at
wavelengths 422 and 445 nm with molar absorbtivity 1.1
104 l mol1 cm1 for each one.
Aluminum and copper were thus determined in the ranges 0.4–2.0 lgml1 and
1.9–3.6 lgml1, respectively, in the presence of one to another. The detection limits were
found to be 1.4 ng ml1 of aluminum and 0.015 lgml1 for copper. The relative standard
deviations were in all instances less than 1.3%. The proposed method was successfully
applied for the simultaneous determination of aluminum and copper in certified reference
aluminum-copper alloys.