A RAPIDLY COLORIMETRIC DETECTION OF ARSENIC AND MERCURY IONS BASED ON SURFACE PLASMON RESONANCE ABSORBANCES OF FUNCTIONALIZED AuNPs IN COSMETICS

In this study, a novel colorimetric method is developed for the detection of arsenic and mercury ions, utilizing the surface plasmon resonance (SPR) properties of AuNPs ( AuNPs = gold nanoparticles) functionalized with APT ( APT = 5 -(3-aminophenyl) tetrazole). Theoretical calculations confirm the findings from UV–Visible spectroscopy and transmission electron microscopy analyses, indicating that APT is electrostatically bound to the surfaces of the AuNPs. The introduction of As 3 + and Hg 2 + ions triggers a coordination reaction with APT, resulting in a reduced interparticle distance among the AuNPs. This change leads to a visible color shift of the solution from wine red to bluish-gray. The detection limits for As 3 + and Hg 2 + are determined to be 0.6 and 0.24 μ g⋅ mL − 1 , respectively, distinguishable to the naked eye. A robust linear correlation is observed between the absorbance ratios and the ion concentrations, with correlation coefficients ( R 2 ) of 0.990 for As 3 + and 0.998 for Hg 2 + . These findings demonstrate that AuNPs functionalized with APT are effective for the quantitative analysis of arsenic and mercury ions. The sensor exhibits high selectivity and excellent resistance to interference, indicating its potential applicability for monitoring As 3 + and Hg 2 + in tap water and cosmetic products.