Highly sensitive direct simultaneous determination of zinc(II), cadmium(II), lead(II), and copper(II) based on in-situ-bismuth and mercury thin-film plated screen-printed carbon electrode

Thin-film disposable screen-printed electrodes modified in situ with bismuth and mercury coatings to enhance the simultaneous sensitivities and the limits of detection of cadmium(II), lead(II), copper(II), and zinc(II) were prepared using anodic stripping voltammetry. Whether the films coated were properly adhered to the surface were checked by energy-dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. The optimum conditions for the best performance of the sensor were investigated. The modification with Bi/Hg film electrode exhibited good analytical performance, with excellent repeatability (RSD <4.0%), reproducibility (RSD <4.0%), and reasonable interferences by various inorganic species. Bi/Hg-SPC electrode also offers low detection limits for Zn(II), Cd(II), Pb(II), and Cu(II), i.e., 0.97 ppb, 0.16 ppb, 0.082 ppb, and 0.64 ppb, respectively. The developed method was applied to a certified reference water sample and a surface water sample taken from the environment by standard addition method and the results are satisfactory. Analytical results obtained with the sensor are comparable to those obtained by the inductively coupled plasma mass spectrometry. [GRAPHICS] .

Automated summary

Thin-film disposable screen-printed electrodes modified in situ with bismuth and mercury coatings were prepared to enhance the sensitivities and limits of detection of heavy metal ions. The Bi/Hg film electrode exhibited good analytical performance with low detection limits, excellent repeatability, and reasonable interferences by various inorganic species.