A new polymeric chromogenic reagent for the determination of copper(II)

A new polymeric chromogenic reagent, poly[allylamine-co-N-4-(8-aminoquinolyl-5-azo)benzylideneallylamine] (PA-FPQ), has been synthesized by condensing polyallylamine (PA) with 5-(4-formylphenylazo)-8-aminoquinoline (FPQ), and its properties studied. In alkaline media, PA-FPQ reacts with copper(II) to form a water-soluble brown complex, whose absorption maximum is at 590 nm. The molar absorptivity (ε) of the complex is 4.1 × 104 l mol −1 cm −1, and Beerʹs law obeyed over the range 0–10 μg ml−1 of copper. Compared to the corresponding low molecular weight FPQ and other heterocyclic azo-chromogenic reagents, PA-FPQ offers considerably improved solubility in water and good selectivity for copper(II), which may be attributed to the incorporation of FPQ into a water-soluble polymer and the effect of the polymeric chain on both reactivity and the reaction microenvironment of the reagent. Also, a simple and selective spectrophotometric method for the determination of copper has been developed and satisfactorily applied to aluminium alloy and bovine liver samples.