Visual detection of melamine in infant formula at 0.1 ppm level based on silver nanoparticles

Abstract

The purpose of this paper is to develop a sensitive and low-cost colorimetric method for detection of melamine using simple circuitry. The stable p-nitroaniline-modified silver nanoparticles (Ag NPs) were synthesized by a zero-length covalent coupling chemistry, which showed sensitivity and selectivity towards melamine. The melamine induces the aggregation of nanoparticles due to electron donor-acceptor interaction between melamine and p-nitroaniline at the Ag NP interface, resulting in a shift in the surface plasmon band and a consequent color change of the Ag NPs from yellow to blue. The color change was monitored using UV-vis spectrophotometry. More importantly, this optical method was successfully utilized to a practical infant formula sample. As low as 0.1 ppm melamine in infant formula could be distinguished upon a color change of solution in two minutes.

One-step synthesis of silver/dopamine nanoparticles and visual detection of melamine in raw milk

“…1A) within 20 min, the typical color of monodispersed AgNPs, which indicated the formation of monodispersed AgNPs. 22 While in the absence of dopamine, the reaction solution remained colorless for 3 hours. The TEM image of Fig.…”

Surface-Enhanced Raman Scattering Liquid Sensor for Quantitative Detection of Trace Melamine in Dairy Products

“…Compared to Au NPs, Ag NPs have some advantages, for example, lower cost of preparation and higher extinction coefficients relative to Au NPs of the same size (Lee, et al, 2007). Therefore, Ag NPs are also good candidates for melamine sensing (Han, et al, 2010; Ping et al, 2012).…”

Comparative Studies on the Quick Recognition of Melamine Using Unmodified Gold Nanoparticles and p‐Nitrobenzenesulfonic Grafted Silver Nanoparticles

“…[16][17][18][19] The resulting citrate-stabilized AuNPs were wine red because of their strong surface plasmon resonance at 520 nm. Upon direct exposure of citrate-stabilized AuNPs to melamine, the color of AuNPs changed from wine red, purple to blue progressively when melamine concentrations increased from 0 to 1.0 mg/L (Fig.…”

“…16 The detailed preparation procedures were carried out with the main modification using p-NBS instead of p-nitroaniline (p-NA) as follows: An ethanolic solution of CS 2 (1 mL, 1 mM) as a linker was added dropwise to a solution of p-NBS (1 mL, 1 mM) as a stabilizer and grafted functional group and sonicated for 5 min. The CS 2 could react with p-NBS to form dithiocarbamates (DTCs).…”