Fast and sensitive visual detection of Fe 2+ using silver nanoparticles modified by 3,3',5,5'-tetramethylbenzidine and 3-mercaptopropionic acid

In this work, a novel sensitive colorimetric sensor was constructed for the determination of Iron (II) (Fe 2+) via by modifying 3,3',5,5'-tetramethylbenzidine and 3-mercaptopropionic acid on the surface of silver nanoparticles. In the presence of Fe 2+ , the modifying groups interacted with Fe 2+, which caused the color of the solution changed, and the absorption peak at 395 nm decreased, while a new absorption peak appeared at 525 nm. This method exhibited good selectivity and sensitivity for the determination of Fe 2+ by observing the color of the system with the naked eye and calculating the ratio of A525 and A404, the linear range was from 0.5×10 -6 M to 1.00×10 -5 M and the limit of visual colorimetric detection was 500 nM. This method has great potential for the rapid detection of iron(II) in environmental samples, including successful applications in tap water and lake water analysis.