A new strategy for the determination of trace Hg²⁺ by 5CB liquid crystal RRS probe based on nanogold amplification and Galvanic replacement reaction

ABSTRACT

In pH 3.1 HCOOH-HCOONa buffer solution, liquid crystal 5CB was used as the probe to generate a strong resonance Rayleigh scattering (RRS) peak at 450 nm. Gold nanoparticles (AuNPs) could catalyse the reaction of phosphomolybdic acid (PMo)-formic acid (FA) to form phosphomolybdenum blue (PMoB), which caused the RRS strength of PMo at 450 nm to decrease linearly. Hg²⁺ could have an electrostatic substitution reaction with AuNPs, thereby inhibiting the catalytic effect of AuNPs, and the RRS peak was enhanced. In the range of 2.5 × 10⁻⁹ mol/L–4.5 × 10⁻⁸ mol/L Hg²⁺, as the concentration of Hg²⁺ increased, the catalytic effect of AuNPs gradually weakened, and the peak value of RRS at 450 nm (ΔI) was linearly increased. The regression equation is ΔI_450nm = 27.988C−5.6159, and the detection limit is 1.0 nmol/L. The method has been used to detect Hg²⁺ in wastewater with satisfactory results.

Graphical abstract

KEYWORDS:

• Mercury
• AuNPs amplification
• electrostatic substitution
• PMob
• 5CB RRS spectral probe
• Ab

Disclosure statement

No potential conflict of interest was reported by the author(s).

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Additional information

Funding

This article was funded by the National Natural Science Foundation of China [21767004].