Use of haematoxylin in an improved method for the determination of ultramicro amounts of aluminium

Abstract

Simple and sensitive methods for the determination of ultramicro amounts of aluminium with haematoxylin and its oxidised form in the presence of cetyltrimethylammonium bromide are described. The complexes formed obeyed Beer's law in the ranges 15–175 and 25–250 µg l^–1 using haematoxylin and oxidised haematoxylin, respectively. The best results for chelate formation were obtained at pH 7.6 and 7.0 with molar absorptivities of 1.7 × 10⁵ and 1.1 × 10⁵ l mol^–1 cm^–1, respectively. The values of Sandell's sensitivity were 0.0002 and 0.0003 µg cm^–2, respectively. The effect of 25 interfering ions was studied. The method has been applied to the determination of aluminium in iron and steel.