Determination of thorium by adsorptive type chemically modified electrode with a polycomplex system

A preconcentration and determination method for thorium in aqueous solution with a tri-n-octylphosphine oxide modified glassy carbon electrode is proposed. In the presence of 2-thenoyltrifluoroacetone, thorium in NaAc-HAc supporting electrolyte is preconcentrated on a modified rotating disk electrode, and a highly sensitive reduction peak is obtained by cathodic stripping voltammetry at -1.10V versus Ag/AgCl. A linear response of reduction peak height and concentration is observed for 1,15 x 10-9 - 1,44 x 10-8 mol.l-1 of thorium and the detection limit is 1,0 x 10-9 mol.l-1. It is very selective and sensitive, with a standard deviation of 3,4% and a recovery of 90 - 110%. (Author)