Determination of Fe(III) Using Diamond Paste Based Electrodes

Voltammetric characterization of new types of electrochemical sensors, based on diamond paste, was performed for Fe(III). The construction of electrodes was done using monocrystalline diamond [natural diamond 1 µ, synthetic diamond 50 µ (synthetic‐1), and synthetic diamond 1 µ (synthetic‐2)] powder and paraffin oil. Differential pulse voltammetry (DPV) was used to study the variation of peak height with the concentration of Fe(III), at 300 mV (vs. Ag/AgCl). The linear concentration ranges were between 10−12 and 10−9 mol/L for the natural diamond with detection limit of 10−13 mol/L; between 10−7 and 10−5 mol/L for synthetic‐1 with a detection limit of 10−8 mol/L; and between 10−11 and 10−5 mol/L for synthetic‐2, with a detection limit of 10−12 mol/L. Fe(III) was determined from four water samples with relative standard deviation values less than 1%. Ions such as, Fe(II), Cr(III), Cr(VI), Mg(II), Mn(II), Cu(II), and Zn(II) do not interfere in the measurements.