Colorimetric detection of melamine based on the interruption of the synthesis of gold nanoparticles

Abstract

A highly sensitive and selective method was presented for colorimetric determination of melamine using gold nanoparticles (AuNPs). AuNPs were synthesized using ellagic acid (EA) as reducer in distilled water at room temperature without adding nanoparticle seeds and stabilizing agent. Melamine could interact with EA through a strong hydrogen-bonding interaction leading to weakening of the EA reducing ability, thus the formation of AuNPs was interrupted and the color of the solution changed from red to pale yellow. The concentration of melamine could be quantified visually or using a UV-vis spectrometer in the wide range from 1.6 × 10⁻⁸ M to 1.6 × 10⁻⁴ M with a correlation coefficient of 0.9961. The detection limit (3σ) was as low as 1.6 × 10⁻⁹ M. This sensor was simple, inexpensive and highly sensitive and could be successfully utilized to detect melamine in pretreated liquid milk products with high recoveries from 93% to 106%. Besides, it exhibited excellent selectivity against other interferences.