Determination of thorium and scandium by indirect chronopotentiometric stripping analysis.
A highly sensitive chronopotentiometric determination of thorium or of scandium is described. It is based on the substitution of thorium or scandium for lead (or zinc) in the lead-EDTA complex, and measurement of the liberated lead by deposition on a mercury film electrode, followed by a chemical oxidation stripping process during which the potential of the mercury electrode is monitored. Thorium has been determined at concentrations in the range 10(-5)-10(-7)M by use of deposition times from 1 min to 1 hr.