Differential Pulse Voltammetric Determination of Selenocystine and Selenomethionine Using SAM nanoSe0/Vc/SeCys-Film Modified Au Electrode

The SAM nanoSe(0)/Vc/SeCys-film modified Au electrode has been prepared to determine selenocystine and selenomethionine. The AFM and SEM showed the special three-dimensional (3D) network structure of the sol-gel films. The affinity between nanoparticles and biomolecules created special chemical characters analyzed by the XRD and fluorescence. The modified electrode was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The modified films partly had resistance in the charge transduction of Fe(CN)(6)(4-/3-), but the less electron-transfer resistance. Differential pulse voltammetric (DPV) determination of selenoamino acids using SAM nanoSe(0)/Vc/SeCys-film modified Au electrode was presented. In PBS (pH 7.0) + 0.1 mol L-1 NaClO4 solution, selenoamino acids yielded a sensitive reduction peak at about +400 +/- 50mV. The peak current had a linear relationship with the concentration of selenoamino acids in the range of 5.0 x 10(-8) - 1.0 x 10(-5) mol L-1, and a 3 sigma detection limit of selenoamino acids was 12 x 10(-8) mol L-1. The relative standard deviation of DPV signals of 0.50 x 10(-6) mol L-1 selenoamino acids was 3.8% (n=8) using the same electrode and was 4.4% (n=5) when using three modified electrodes prepared at different times. The content of selenoamino acids in the organo-selenium powder were determined by DPV The results showed 71.5 mu g g(-1) of SeCys and 65.1 mu g g(-1) of SeMet in the organo-selenium powder.