The proposed work deals with the utilization of three carbon-based electrode substrates such as boron-doped diamond, glassy carbon and carbon paste for the preparation of in situ bismuth film modified electrodes. Such modified electrodes were subsequently used for the differential pulse anodic stripping voltammetric determination of heavy metal cations (Zn2+, Cd2+ and Pb2+) individually and simultaneously using similar experimental conditions (0.1 mol l−1 acetic buffer solution of pH 4.5 as supporting electrolyte with the addition of 0.1 mmol l−1 Bi3+, deposition potential of −1.4 V and deposition time of 120 s). The results showed that the modification step mostly enhanced the deposition and stripping process of studied cations when compared to the bare electrode substrates. A boron-doped diamond electrode was selected as the substrate for modification and the procedure was applied to the real sample analysis including water sample (certified reference material) and wastewater sample. Using the standard addition method the concentrations of particular heavy metals were quantified and the determined values were in a good agreement with those obtained by the reference method — high resolution atomic absorption spectroscopy with electrothermal atomisation and continual radiation source. This fact highlights that the developed in situ bismuth film modified boron-doped diamond electrode is a suitable electrochemical sensor to be applied to routine analysis of water samples containing heavy metals.

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Abstract:The present article describes a method of determination of low antimony concentrations using a graphite furnace AAS technique after electrochemical preconcentration. A 2-electrode flow-through cell was developed with a working electrode made of gold-coated porous carbon and an accessory Pt electrode. This cell worked in online coupling with the graphite furnace atomizer. Accumulation occurred from the 6 M hydrochloric acid solution and 2 M nitric acid was used to dissolve and transport antimony into the sampling loop. The sampling loop was placed on a 6-way valve. The preconcentrated solution was transported to the atomizer using an air jet. The detection limit (3 σ) was 0.02 µ g/L and the overall linear range was 0.05-10 µ g/L. The method could be used only to determine the concentration of total inorganic antimony. The method was validated through analysis of certified reference materials and various water samples. Good agreement with the reference values was observed in all cases.