Development of a new biomimetic sensor based on an FeIIIFeII complex for the determination of phenolic compounds

The dinuclear iron complex, [FeIIIFeII(BPBPMP)(OAc)2]ClO4, containing the unsymmetrical ligand, 2-bis[{(2-pyridylmethyl)-aminomethyl}-6-{(2-hydroxybenzyl)(2-pyridylmethyl)}-aminomethyl]-4-methylphenol (H2BPBPMP), has been described as being the first synthetic analogue for the redox properties of uteroferrin. This iron complex was employed in the construction of a new biomimetic sensor for the determination of phenolic compounds by square-wave voltammetry. The responses under optimized conditions were obtained for a 75:15:10% (w/w/w) composition of the graphite powder:Nujol:iron complex, 0.1 mol L−1 phosphate buffer solution (pH 7.0) and 4.5 × 10−5 mol L−1 hydrogen peroxide. From the several phenolic compounds available (carbidopa, catechol, dopamine, hydroquinone, l-dopa and methyldopa), dopamine was selected, used for optimization of the biomimetic sensor and applied in determinations in pharmaceutical formulations. The analytical curve was linear for dopamine concentrations from 5.0 × 10−5 to 6.5 × 10−3 mol L−1 (r = 0.9993). The recovery of dopamine from pharmaceutical sample ranged from 95.8 to 104.2% and the relative standard deviation was 2.6% for a solution containing 3.0 × 10−3 mol L−1 dopamine (n = 12). The lifetime of this biomimetic sensor was 6 months (at least 800 determinations). The results obtained for dopamine in pharmaceutical samples using the proposed biomimetic sensor and those obtained by the official method are in agreement at the 95% confidence level.