Electrode Modified with Langmuir–Blodgett (LB) Film of Calixarenes for Preconcentration and Stripping Analysis of Hg(II)

Determination of Mercury (II) Ion on Aryl Amide-Type Podand-Modified Glassy Carbon Electrode

A new voltammetric sensor based on an aryl amide type podand, 1,8-bis(o-amidophenoxy)-3,6-dioxaoctane, (AAP) modified glassy carbon electrode, was described for the determination of trace level of mercury (II) ion by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A well-defined anodic peak corresponding to the oxidation of mercury on proposed electrode was obtained at 0.2 V versus Ag/AgCl reference electrode. The effect of experimental parameters on differential voltammetric peak currents was investigated in acetate buffer solution of pH 7.0 containing 1 × 10−1 mol L−1NaCl. Mercury (II) ion was preconcentrated at the modified electrode by forming complex with AAP under proper conditions and then reduced on the surface of the electrode. Interferences of Cu2+, Pb2+, Fe3+, Cd2+, and Zn2+ions were also studied at two different concentration ratios with respect to mercury (II) ions. The modified electrode was applied to the determination of mercury (II) ions in seawater sample.

An optical sensor for mercury ion based on the fluorescence quenching of tetra(p-dimethylaminophenyl)porphyrin

An optical sensor for mercury ion (Hg(2+)), based on quenching the fluorescence of the sensing reagent porphyrin immobilized in plasticized poly(vinyl chloride) (PVC) membrane, has been developed. The responses to mercury ion were compared for the sensors modified with three porphyrin compounds including 5,10,15,20-tetraphenylporphyrin (TPP), tetra(p-dimethylaminophenyl)porphyrin (TDMAPP) and tetra(N-phenylpyrazole) porphyrin (TPPP). Among them, TDMAPP showed the most remarkable response to Hg(2+). The drastic decrease of the TDMAPP fluorescence intensity was attributed to the formation of a complex between TDMAPP and Hg(2+), which has been utilized as the fabrication basis of a Hg(2+)-sensitive fluorescence sensor. The analytical performance characteristics of the TDMAPP modified sensor was investigated. The response mechanism, especially involving the response difference of three porphyrin compounds, was discussed in detail. The sensor can be applied to the quantification of Hg(2+) with a linear range covering from 4.0x10(-8)molL(-1) to 4.0x10(-6)molL(-1). The limit of detection was 8.0x10(-9)molL(-1). The sensor exhibited excellent reproducibility, reversibility and selectivity. Also, the TDMAPP-based sensor was successfully used for the determination of Hg(2+) in environmental water samples.