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

• Published in: Liquid crystals 2022-03, Vol.49 (4), p.559-565
• Main Authors: Liang, Aihui, Shu, Yiyi, Huang, Xiaofang, Li, Dan, Zhi, Shengfu, Li, Chongning, Jiang, Zhiliang
• Format: Article
• Language: English
• Subjects: 5CB RRS spectral probe; AuNPs amplification; Buffer solutions; electrostatic substitution; Formic acid; Gold; Liquid crystals; Mercury; Mercury (metal); Nanoparticles; Phosphomolybdic acid; PMob; Rayleigh scattering; Resonance scattering; Substitution reactions; Wastewater
• ISSN: 0267-8292; 1366-5855
• DOI: 10.1080/02678292.2021.1985175

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. Hg 2+ 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 Hg 2+ , as the concentration of Hg 2+ 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 Hg 2+ in wastewater with satisfactory results.