Microelectrodes modified with [M-III(bpy)(3)](ClO4)(3) (M = Co and Fe) as analytical sensors for fullerenes in flow injection analysis

Catalytic electroreduction of fullerene (C-60) at An or Pt microelectrodes covered with [M-III(bpy)(3)](ClO4)(3) (M = Co and Fe, and bpy = 2,2'-bipyri dine) was investigated. Under constant potential oxidation in acetonitrile/ toluene (1:4, v/v) solution containing [M-II(bpy)(3)](2+) complexes and (n- BU)(4)NClO4 as a supporting electrolyte, the microelectrodes were modified with electrochemically inactive [M-III(bpy)(3)](ClO4)(3) films. The chemica l reduction of electrochemically formed films by C-60(-) results in enhance ment of fullerene reduction current enabling thus for sensing Of C-60. Anal ytical performance of electrodes modified with [Co-III(bpy)(3)](ClO4)(3) wa s better than those covered with [Fe-III(bpy)(3)](ClO4)(3), Microelectrodes modified with [Co-III(bpy)(3)](ClO4)(3) were used to quantify the fulleren e concentration in flow injection analysis. In the proposed analytical proc edure the solution containing both the [Co-II(bpy)(3)](2+) complex and the C-60 analyte was injected to the flowing stream of an acetonitrile/toluene (1:4, v/v) mixture containing (n-BU)(4)NClO4. The triangular potential wave form. was applied to the gold microelectrode. During the positively going p otential scan the electrode was covered by an electrochemically inactive [C o-III(bpy)(3)](ClO4)(3) layer. In the cathodic scan, the catalytic current Of C-60 reduction was recorded. A dependence of a current signal of catalyt ic C-60 reduction on fullerene concentration was linear in a concentration range 5 x 10(-7) to 2 x 10(-5) mol dm(-3). Reproducibility of the electrode response under FIA conditions was good.