Graphic Data Analysis and Complex Formation Curves as Modelling and Optimization Tools in Potentiometric and Voltammetric Speciation Studies of a Pb?(TAPSO)x?(OH)y System

The formation of complex species between lead and TAPSO, a commercialized biological buffer, was evidenced and discussed. Formation constants of Pb? (TAPSO)_x? (OH)_y system have been studied by direct current polarography and by glass electrode potentiometry at fixed total–ligand and total–metal concentration ratio and varied pH, at 25.0 °C and ionic strength set to 0.1 M KNO₃. The graphic analysis revealed to be a very powerful tool in the prediction and refinement operations of Pb–(TAPSO)_x? (OH)_y system. The proposed final model for this system is: PbL, PbL₂, PbL₂(OH) and PbL₂(OH)₂, with stability constants values, as log β, of 3.7±0.1, 6.6±0.1, 12.9±0.1 and 17.8±0.1, respectively.