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Browsing by Author "Boubaker, Elyes"

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  • Analysis of cadmium, copper and lead ions in wine by ASDPV with a lab-made graphite composite working electrode
    Publication . Boubaker, Elyes; Dias, L.G.; Estevinho, Leticia M.; Mokkadem, Yassin
    The purpose of the current study was to quantify the concentrations of copper, cadmium, lead ions in wine using ASDPV with a lab-made graphite composite electrode. A first study involved analysis of a reversible redox solution of K3[Fe(CN)₆] with response surface methodology in order to verify the CV dependency with scan rate and potential step, as well the DPV dependency with scan rate, potential pulse and potential step. For the DPV analysis, the conditions selected were 0.03 V/s for the scan rate, 0.01 V for the step potential, and 0.04 V for the pulse potential. With these experimental conditions, the DPV data from a full factorial design using two concentration levels of the three heavy metals allowed to verify the independence between the calibrations of each metal. The analysis of 8 samples of Portuguese and Spanish wines by ETAAS allowed to verify that only copper levels were detected and quantified, obtaining Cu2+ concentrations varying between 0.011 and 0.535 mg/L. Considering the heavy metals trace levels, the ASDPV technique was selected, with the 4 min deposition step for standard calibration solution and sample solutions, which demanded an assisted digestion with HNO3 and H2O2. The ASDPV showed higher sensibility toward the copper (slope of 22 μA.L.mg-1), than cadmium (slope of 14.2 μA.L.mg-1) and lead (slope of 13.5 μA.L.mg-1). Only copper levels were measured in wine samples by ASDPV, within the range of 0.09 to 0.55 mg/L, being 0.91 times lower than those obtained by ETAAS. Overall, the cheap lab-made graphite composite working electrode allows to analyze simultaneously three heavy metals using the ASDPV technique. Its analytical performance allows considering its application in the voltammetric analysis of wines. However, there is space for improvement by optimizing the experimental procedure of solutions preparations for ASDPV analysis which will be addressed in future work.
    2022Master thesis Open access Show more