Electrochemical behavior of [Re-I(DMPE)(3)](+), where DMPE = 1,2-bis(dimethylphosphino)ethane, at perfluorosulfonated ionomer modified electrodes

The perfluorosulfonated ionomer Nafion shows potential utility as a polymer film to enhance the electrochemical detection of [Re-I(DMPE)(3)](+), where DMPE = 1,2-bis(dimethylphosphino)ethane. [Re-I(DMPE)(3)](+), a nonradioactive radiopharmaceutical analog for heart imaging, partitions strongly into Nafion films on glassy carbon. Well-defined, chemically reversible cyclic voltammograms are obtained for the [Re-I(DMPE)(3)](+)/[Re-II(DMPE)(3)](2+) couple with E-o' shifted positively by 60 mV relative to its value on bare glassy carbon. [Re-I(DMPE)(3)](+) partitions into Nafion more strongly than the oxidized form, [Re-II(DMPE)(3)](2+). The detection limit for [Re-I(DMPE)(3)](+) by cyclic voltammetry was improved by 2-3 orders of magnitude by the Nafion film. Differential pulse voltammetry for oxidation of [Re-I(DMPE)(3)](+) at the Nafion-modified electrode has a detection limit of 2.5 x 10(-9) M compared to 1.0 x 10(-7) M at the bare electrode. A preconcentration factor of 1 x 10(6) for partitioning of [Re-I(DMPE)(3)](+) from 0.05 M NaCl into Nafion on a glassy carbon electrode was measured.