Preconcentration of trivalent lanthanide elements on a mercury film from aqueous solution using rotating disk electrode voltammetry.

An approach to concentrate trivalent lanthanide elements into or onto mercury film electrodes supported on rotating disk glassy carbon electrodes in small volumes (<or=1000 microL) is described. La(3+) was used as a model for the trivalent f-element cations because its standard potential is the most negative. La(3+) cathodically sorbed onto or into a preformed Hg film electrode from LiCl. After initial characterizations, Nd(3+), Eu(3+), Gd(3+), Ho(3+), and Lu(3+) were tested individually and in a mixture. ICPMS analyses demonstrated that these elements could be accumulated cathodically from LiCl solution and stripped anodically in 2% HNO(3), both individually and as a mixture. These cations can be electrochemically preconcentrated onto and stripped from the electrode in 5 min, a vast improvement over traditional approaches such as evaporation that require hours to days in some cases.