Development of a novel method for determination of mercury based on its inhibitory effect on horseradish peroxidase activity followed by monitoring the surface plasmon resonance peak of gold nanoparticles

•Development of a simple & accurate method for indirect spectrophotometer determination of Hg2 +.•The LSPR of Au–NPs is used for indirect determination of Hg2 +.•Combination of inhibitory effect of Hg2 +on HRP & LSPR of Au–NPs for determination of Hg2 +.

A highly sensitive and simple indirect spectrophotometric method has been developed for the determination of trace amounts of inorganic mercury (Hg2 +) in aqueous media. The method is based on the inhibitory effect of Hg2 + on the activity of horseradish peroxidase (HRP) in the oxidation of ascorbic acid by hydrogen peroxide followed by the reduction of Au3 + to Au–NPs by unreacted ascorbic acid and the measurement of the absorbance of localized surface plasmon resonance (LSPR) peak of gold nanoparticles (at 530 nm) which is directly proportional to the concentration of Hg2 +. Under the optimum conditions, the calibration curve was linear in the concentration range of 1–220 ng mL− 1. Limits of detection (LOD) and quantification (LOQ) were 0.2 and 0.7 ng mL− 1, respectively and the relative standard deviation at 100 ng mL− 1 level of Hg2 + was 2.6%. The method was successfully applied to the determination of mercury in different water samples.

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