Colorimetric detection of hg(Ii) ion using silver nanoparticles capped with 3-hydroxybenzoic acid

In this paper, we report for the first time the simple method for detection of Hg(II) ion in an aqueous medium using silver nanoparticles capped with 3-hydroxybenzoic acid. Silver nanoparticles capped with 3-hydroxybenzoic acid were prepared by reduction of the silver ion with 3-hydroxybenzoic acid and without surface functionalization. The formation of silver nanoparticles was characterized by a UV-Visible spectrophotometer. The yellow colloid of prepared silver nanoparticles capped with 3-hydroxybenzoic acid showed a surface plasmon resonance peak at 420 nm. The ability of silver nanoparticles capped with 3-hydroxybenzoic acid in detection was tested by doing a reaction with several metal ions individually (Na(I), K(I), Cu(II), Zn(II), Ca(II), Mg(II), Hg(II), Mn(II), Ni(II), Pb(II), and Co(II)). It was found that silver nanoparticles capped with 3-hydroxybenzoic acid highly selective to Hg(II) and then the prepared silver nanoparticles were developed for detection of Hg(II) ion. Addition of 1 mL Hg(II) ion into 4 mL the as-prepared silver nanoparticles reduced the peak of surface plasmon resonance spectra, and the reduction of peak intensity was proportional to the concentration of Hg(II) ion. A good linear relationship (R² = 0.998) between absorbance at 420 nm and concentration of Hg(II) over the range 1.0x10^-3 to 5.5x10^-3 M was obtained. Silver nanoparticles capped with 3-hydroxybenzoic acid were highly sensitive to Hg (II) ion with the detection limit down to 4.7x10^-5 M. Application the method to the real water sample showed the excellent result with recovery ranged from 98 to 101. The proposed method was found to be useful for the colorimetric detection of Hg(II) ion in an aqueous medium. © 2019, Universitas Jenderal Soedirman. All rights reserved.