Simple and rapid detection of free 3-monochloropropane-1,2-diol based on cysteine modified silver nanoparticles

A rapid colorimetric method using cysteine-modified silver nanoparticles (Cys-AgNPs) is applied for the detection of 3-monochloropropane-1,2-diol (3-MCPD). Indeed, in the presence of 3-MCPD, the color of Cys-AgNPs solution changes from yellow to pink within five minutes at 100 °C and pH 9.3. This change is mainly attributed to the ability of amino group of cysteine to react with 3-MCPD to form N-(2,3-dihydroxypropyl)-amino acid grafted on AgNPs (3-MCPD-Cys-AgNPs) in alkaline medium. This color change makes 3-MCPD to be clearly detectable by unassisted visual means even at 0.1 μg⋅mL−1. Besides, using UV–Vis spectroscopic technique, a linear range from 0.1 μg⋅mL−1 to 1.25 μg⋅mL−1 for 3-MCPD detection is obtained, with a calculated detection limit of 0.084 μg⋅mL−1. These results suggest that this sensing technique is sensitive to 3-MCPD and may have a substantial application in the rapid detection of food contaminants particularly, where quality and safety of food products are paramount concern.