Spectrophotometric determination of aluminum with bromopyrogallol red in the presence of surfactants

Spectrophotometric methods are described for the determination of microgram amounts of aluminum based on the formation of a ternary complex between the metal, bromopyrogallol red, and cetyltrimethylammonium bromide or nonylphenol tetradecaethylene glycol ether. The complexes have absorbance maxima at 627 and 612 nm, respectively, with molar absorptivities of 5.0 × 10⁴ and 2.2 × 10⁴ liter mol^?1 cm^?1. Numerous metals interfere. Aluminum can be easily separated by extraction of interfering ions with cupferron.