Spectrofluorimetric and spectrophotometric determination of aluminium with the salicyloylhydrazones of pyridine-2-aldehyde and pyridoxal

Abstract

The analytical applications of the salicyloylhydrazones of pyridine-2-aldehyde (SHPA) and pyridoxal (PSH) are described. PSH reacts with aluminium at pH 2.0 to produce a yellow complex (λ_max.= 420 nm, ε= 2.5 × 10⁴ l mol^–1 cm^–1); another complex can be detected at pH 4.75 (λ_max.= 425 nm, ε= 3.1 × 10⁴ l mol^–1 cm^–1). SHPA reacts with aluminium at pH 5.4 to give a complex having a blue fluorescence (λ_ex.= 382 nm, λ_em.= 440 nm) and both reagents are compared. Sensitive and selective methods are proposed for the determination of aluminium ions. The yellow aluminium - PSH complex formed in acid medium (pH = 2.0) has been used for the determination of aluminium in samples of steel and a Portland cement.