Synthesis and Structural Characterization of New Macrocyclic Ester. Study as an Immobilization Agent for Determination of Lead by Anodic Stripping Voltammetry

摘要

New macrocyclic ester (L) was yielded through reaction of catechol with isophthaloylchloride and isolated as white solid, air stable at room temperature. L was characterized by melting point, mass spectra, FTIR and NMR (1H, 13C) spectroscopy. The molecular structure was determined by single- crystal X-ray diffraction. The macrocyclic compound was evaluated to determine ultra-trace concentrations of Pb (II) by anodic stripping voltammetry in the presence of Cd(II). The method is based on the formation of a complex between lead and the macrocyclic ester, immobilized on a vitreous carbon electrode, allowing the oxidation of lead by voltammetric scan, using square wave modulation method. Anodic peak current was observed at -0.20 V for Pb(II). Under the best experimental conditions (pH 4.0; L concentration 10.0 mmol L-1; accumulative potential (Eacc) -0.8 V and accumulative time (tacc) of 60 s) anodic peak current was proportional to the Pb (II) concentration up to 80.0 μg L-1, with a detection limit (3σ) of 0.33 μg L-1. The proposed method was validated by determining Pb(II) in model solution with ultra-pure water with satisfactory results.