Trace analysis of hydrogen sulfide by monitoring As(III) at a poly(l-lactide) stabilized gold nanoparticles modified electrode

An indirect electrochemical approach for the determination of sulfide by measuring the inhibited oxidation current of As(III) in HCl medium using a poly(l-lactide) stabilized gold nanoparticles modified screen-printed electrode (designated as PLA-AuNP/SPE) is described in this work. The PLA-AuNP/SPE is applied effectively to detect As(III) in HCl medium and can be tolerable from the interference of Cu, Cd, Fe, Zn, Mn and Ni and hence provides a direct and selective detection method for As(III) in natural waters. An substantial decrease in the oxidation peak current of As(III) is observed in the presence of sulfide due to the formation of As2S3 complex. Surface analysis by XPS together with electrochemical and Raman spectroscopic characterization were used to elucidate the detection mechanism. Under the optimal experimental conditions, a calibration plot with a wide linear range up to 700 μM was achieved with a detection limit (S/N = 3) of 0.04 μM. The sensitivity observed in present study is good enough to detect sulfide at levels lower than the current EPA standard. The proposed electrochemical approach was successfully used for the determination of sulfide in acid rain and hot spring water.