title: A synergistic coordination strategy for colorimetric sensing of chromium(III) ions using gold nanoparticles.
abstract: We report a simple, facile, and reliable colorimetric system for detection of chromium(III) ions (Cr3+) using citrate- and thiourea-modified gold nanoparticles (AuNPs). The colorimetric sensing strategy is based on the synergistic coordination interaction of citrate and thiourea toward Cr3+on the surface of AuNPs, leading to the aggregation of AuNPs which produces a color change from red to purple. Under the optimal conditions, this colorimetric sensing system shows an excellent selectivity and sensitivity for Cr3+, and the limit of detection (LOD) is estimated to be 0.05 μM at a signal-to-noise ratio of 3, which is far below the current standard stipulated by U.S. Environmental Protection Agency (1.9 μM). Moreover, this LOD is one and a half orders of magnitude lower than those of previously reported modified AuNPs-based colorimetric methods. Visual color change can be observed when 50 μM of Cr3+was introduced to the sensing system. Furthermore, this colorimetric sensing system can be employed for detection of Cr3+in diluted natural water samples.
authors.affiliation: School of National Defence Science & Technology, Southwest University of Science and Technology, Mianyang, Sichuan, 621010, China.
authors.forename: Dengying
authors.initials: D
authors.lastname: Long
authors.affiliation: School of National Defence Science & Technology, Southwest University of Science and Technology, Mianyang, Sichuan, 621010, China. yuhaili-119@163.com.
authors.forename: Haili
authors.initials: H
authors.lastname: Yu
keywords: Citrate; Colorimetry; Cr3+; Gold nanoparticles; Thiourea