Use of carbon black based electrode as sensor for solid-state electrochemical studies and voltammetric determination...

For the first time carbon black based electrode modified with paraffin was applied as a sensor on voltammetry of immobilized microparticles (VIMP) approach for determination of lead solid residues in hair dye samples. The solid microparticles of Pb(II) (Pb(CH₃COO)_2(s)) immobilized into the carbon paste sensor containing carbon black and paraffin were firstly reduced at initial potentials and further reoxidized at around -0.60 V during anodic scan. Electroanalytical parameters as well as supporting electrolyte composition, and pH were also evaluated. An analytical curve in 0.2 mol L^-1 phosphate buffer solution (pH 5.0) from 0.04 to 3.2 μg (R² = 0.999) with detection and quantification limits of 4 and 13 ng, respectively, were achieved. The method was applied to quantify lead solid residues in hair dye samples without previous mineralization or complex sample pre-treatment. Besides adequate repeatability, stability and selectivity of the developed sensor based on VIMP features, the method using carbon black based sensor was considered advantageous comparing to the results recorded by a spectrometric method (relative error lower than 8%) from several analytical viewpoints.