Photometric Determination of Traces of Aluminum in Foodstuffs With p-Acetylchlorophosphonazo as Color Reagent

In an acetate buffer medium of pH 4.3,a blue-violet complex was formed by the reaction of Al(Ⅲ) with p-acetylchlorophosphonazo (abbreviated as CPA-pA) with its molar ratio of 1 to 1. Absorption maxima of the complex was found at the wavelength of 604 nm and its apparent molar absorptivity was 9.92×103L·mol-1·cm-1. Beer′s law was obeyed over the range within 0.60 mg·L-1 of aluminum(Ⅲ). The proposed method has been applied to the determination of aluminum in 3 samples of foodstuff,RSD′s (n=7) values calculated from the analytical results were in the range from 1.03% to 2.16%,and values of recovery found were in the range of 96.5% to 101.0%.