Colorimetric detection of nickels using silver nanoplates modified with glutathione and L-cysteine

Abstract

A novel colorimetric sensor based on silver nanoplates (AgNPls) for detecting nickel ions (Ni(II)) has been developed. Glutathione (GSH) and L-cysteune (Cys) have been used to modify the AgNPls surface, exhibiting extremely high selectivity towards Ni(II) over other metal ions under specific conditions. Upon addition of Ni(II) to the modified AgNPls solution, color change can be clearly observed by naked eyes due to the aggregation of AgNPls induced by the binding between Ni(II) and the ligands. To verify a complete self-assembly of the GSH and Cys onto AgNPls suface, the modified AgNPls were characterized using fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), and transmission electron microscopy (TEM), respectively. In addition, various parameters for Ni(II) quantification including modifier ratio, pH effect, incubation time, and interferences were investigated. From UV-vis spectrophotometric measurement of Ni(II) under optimal conditions, a quantitative linearity was established in the range of 10-150 ng/mL (R ² = 0.9971) with the detection limit of 7.02 ng/mL or 120 nM (S/N=3), determine Ni(II). Furthermore, this sensor has been applied to the determination of Ni(II) in real gold plating solutions from a jewelry factory with satisfactory results. Overall, this alternative approach presents a simple, rapid rapid, sensitive, and selective detection of Ni(II).