Xanthan gum-capped Chromia Nanoparticles (XG-CrNPs): A promising nanoprobe for the detection of heavy metal ions.

The present study reports on the selective and sensitive detection of metals using xanthan gum-capped chromia nanoparticles (XG-CrNPs). The nanoparticles were synthesized by the chemical reduction method using sodium borohydride and xanthan gum as the reducing and capping agents, respectively. The synthesis of XG-CrNPs was confirmed by the appearance of the two absorption peaks at 272 nm and 371 nm in the UV-visible region. The nanoparticles have been extensively characterized by FTIR, TEM-EDX, XRD, and TGA analyses. The well-dispersed XG-CrNPs exhibited a quasi-spherical structure with an average particle size of 3 nm. A significantly low amount (2 μg/L) of XG-CrNPs was used for selective and sensitive detection of heavy metal ions. It showed excellent metal detecting properties by quenching its band gap signal which was extraordinarily conspicuous for Co(II), Hg(II), and Cd(II) in comparison to other metal ions like Ag(I), Ba(II), Mg(II), Mn(II), Ni(II), and Zn(II). The limit of detection of Co(II), Cd(II), and Hg(II) with this nanoprobe was found to be 2.167 μM, 1.065 μM, and 0.601 μM respectively. The nanoparticles manifested higher shelf-life and can be reused up to three consecutive cycles where most of its activity was conserved even after being used. Thus, it may find use in metal sensor devices for the detection of hazardous metals.