A screen-printed voltammetric electronic tongue for the analysis of complex mixtures of metal ions

Abstract

A voltammetric electronic tongue was constituted by four screen-printed modified electrodes: a carbon nanofiber modified electrode, an ex-situ antimony film electrode prepared from carbon nanofiber modified electrode, and two carbon nanofiber electrodes chemically modified withCys and GSH. The tongue was successfully applied to the analysis of a complex mixture of metal ions (4 analytes and 2 interferences) by differential pulse anodic stripping voltammetry. Each sensor was firstly studied for the determination of each metal separately confirming that all electrodes showed differentiated response for the metals. The obtained voltammetric signals provided by the sensor array were processed by Partial Least Squares regression (PLS) to resolve the overlapped nature of the obtained multimetal stripping measurements. This PLS model was built considering a hierarchical model in order to reduce the large amount of data. The method was applied to synthetic mixtures of Cd(II), Pb(II), Tl(I), and Bi(III) in the presence of Zn(II) and In(III) at the levels of μg L-1 and successfully validated with correlation coefficients of both calibration and prediction higher than 0.9 obtained from predicted vs. expected concentration graphs. Moreover, the simultaneous determination of Cd(II), Pb(II), Tl(I), and Bi(III) in the presence of Zn(II) and In(III) in a spiked tap water was also satisfactory achieved, providing comparable results to those obtained by ICP-MS.