pH Dependence on Colorimetric Detection of Hg2+ by Histidine-Functionalized Gold Nanoparticles

Dewi Eviane (Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara, Yogyakarta 55281, Indonesia)
Dwi Siswanta (Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara, Yogyakarta 55281, Indonesia)
Sri Juari Santosa (Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara, Yogyakarta 55281, Indonesia)

Indonesian Journal of Chemistry
Vol 20, No 4 (2020)

In this study, we successfully developed gold nanoparticles capped with histidine (His-AuNPs) for Hg2+ detection using trisodium citrate as the reducing agent. The optimum pH for the detection of Hg2+ by His-AuNPs was 12. The addition of Hg2+ to the His-AuNPs caused the color change from red to black-blue, which is readily detectable by the naked eye. This color change is followed by a decrease in the intensity of the primary Surface Plasmon Resonance (SPR) peak at a wavelength (λ) of 525 nm and an increase in the secondary peak at λ = 650 nm. His-AuNPs effectively detected Hg2+ with limits of detection and quantitation of 1.77 µM and 5.89 µM, respectively. His-AuNPs exhibited good performance for the detection of Hg2+ in waste water collected from a steel industrial facility in Banten Province, with a recovery and a percent relative standard deviation of 115% and 1.02%, respectively.