Aluminium readily reacts with DDAB (the title compound) in the presence of ethylenediamine (en) to form a stable fluorescent complex, which showed a maximum fluorescence intensity at pH values from 6.9 to 7.6. The fluorescence intensity of the complex increased remarkably with the addition of dioxane to its aqueous solution. The analytical procedure was as follows: Take 0?9 cm
3 of a sample solution containing less than 3 μg of aluminium, and add 15 cm
3 of a buffer solution described below and 1 cm
3 of a 0.02% DDAB solution in dioxane. Dilute the mixture to 25 cm
3 with water. After standing for 15 min, measure the fluorescence intensity at 575 nm with excitation wavelength of 485 nm by using 0.01?0.5 μg cm
-3 of a Rhodamine B solution as the reference standard. When analysis of samples solution containing 0.005?0.05 μg of aluminium were required, 1 cm
3 of a 0.004% DDAB solution was used. The buffer solution (pH 7.4) was prepared by adding 20 cm
3 of en and 65 cm
3 of (1+1) acetic acid to 200 cm
3 of methanol and then diluting it to 500 cm
3 with dioxane. The composition of the complex formed under the analytical conditions was Al:DDAB:en:acetate=1:1:2:1. En also acted as a masking agent of interfering ions. The proposed procedure was applied to the determination of aluminium in copper alloys.
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