title: 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.
authors.affiliation: Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, PR China.
authors.forename: Cuiping
authors.initials: C
authors.lastname: Han
authors.forename: Haibing
authors.initials: H
authors.lastname: Li
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D003124:Colorimetry / Q000379:methods*; D006801:Humans; D007223:Infant; D041943:Infant Formula / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors; D014227:Triazines / Q000032:analysis*
chemical_list: D000814:Aniline Compounds; D014227:Triazines; C019498:4-nitroaniline; D012834:Silver; C011907:melamine