One-Pot Interference-Based Colorimetric Detection of Melamine in Raw Milk via Green Tea-Modified Silver Nanostructures

Abstract

Detection of melamine has proven to be a challenge, requiring the use of complex analytical techniques. This study introduces an innovative, straightforward one-pot technique for qualitative assessment of the milk adulterant melamine. Originally, silver nanoparticles (AgNPs) were synthesized by utilizing green tea extract, which acted as both a reducing and sensing element. The synthesized AgNPs were characterized using UV–vis spectroscopy, X-ray diffraction, zeta potential, transmission electron microscopy, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. Melamine, rich in –NH2 groups, interacts with the biopolyphenols of green tea extract through hydrogen bonding. This interaction inhibits the formation of nanoparticles, resulting in a noticeable colorimetric response. The data obtained were confirmed by a standard UV–vis spectrophotometer and validated by the high-performance liquid chromatography technique. The limit of detection achieved by this scheme was quite low, falling below the permissible levels recommended by government bodies, e.g., the Food Safety and Standards Authority of India (FSSAI).

Elucidating impact of solvent and pH in synthesizing silver nanoparticles via green and chemical route

“…Metal nanostructures have attained considerable attention in the recent times due to their exceptional properties like optical, electrical and physiochemical [1]. Among these, silver nanoparticles (AgNPs) are utilised in numerous applications namely, catalysis [2], biomedical [3], theragnostic [4], photothermal conversion [5], and sensing [6][7][8][9][10][11], etc. These NPs possess a unique characteristic, which is enhanced absorbance and scattering of light of different…”