A new multivariate standard addition strategy for stripping voltammetric electronic tongues: Application to the determination of Tl(I) and In(III) in samples with complex matrices.

A new multivariate standard addition strategy applicable to stripping methods was proposed as an extention of the classical univariate standard addition method for the resolution of complex samples involving overlapped peaks and complex matrices. The proposed strategy consists in alternate additions of the considered analytes and the further extrapolation to a simulated blank solution measured by skipping the preconcentration step (deposition time = 0). This calibration approach was successfully tested in tonic water samples spiked with Tl(I) and In(III) using a sensor array based on a SeCyst-SPCNFE and an ex-situ-BiSPCE, providing good concordance between replicates and much better accuracy than the usual multivariate external calibration method.

Inorganic arsenic speciation by differential pulse anodic stripping voltammetry using thoria nanoparticles-carbon paste electrodes.

Two novel thoria (ThO2) nanoparticles-carbon paste electrodes were used to evaluate an anodic stripping voltammetric method for the direct determination of arsenite and total inorganic arsenic (arsenite plus arsenate) in water samples. The effect of Ag((I)), Cu((II)), Hg((II)), Sb((III)) and Se((IV)) ions on the electrochemical response of arsenic was assayed. The developed electroanalytical method offers a rapid procedure with improved analytical characteristics including good repeatability (3.4%) at low As((III)) concentrations, high selectivity, lower detection limit (0.1 µg L(-1)) and high sensitivity (0.54 µA µg(-1) L). The analytical capability of the optimized method was demonstrated by the determination of arsenic in certified reference materials (trace elements in natural water, trace elements in water and coal fly ash).