Colorimetric determination of aluminum(III) based on the aggregation of Schiff base-functionalized gold nanoparticles

Abstract

The authors describe a colorimetric method for the determination of Al(III) using surface modified gold nanoparticles (AuNPs). Citrate capped AuNPs were functionalized, by self-assembly, with the Schiff base obtained from 2-hydroxy-1-naphthaldehyde and 2-aminoethanethiol. The modified AuNPs were characterized by transmission electron microscopy and FTIR. Complexation of Al(III) ions by the Schiff base on the AuNPs results in self-aggregation of the AuNPs which is accompanied by a color change from red to blue which can be monitored visually or by UV–vis spectroscopy. Absorbance varies linearly with the Al(III) concentration in the range from 9 to 23 μM, and the lower detection limit is 0.29 μM (at 3 So/k). The method was applied to the determination of Al(III) in (spiked) samples of boiler water and urine.