Realisation of ferrocene reference electrode in concentrated HF media

A carbon paste electrode (CPE) modified with ferrocene (Fc) was constructed by incorporating ferrocene (Fc¯) into the carbon paste matrix. CPE in presence of ferricinium (Fc + ) ion in concentrated hydrofluoric acid (HF) (0.1 - 14.0 M) media without junction potential plays the role of a practical reference electrode (FRE) in concentrated acids. Fc + was easily prepared in biphasic medium HF-toluene by the quantitative oxidation of ferrocene by the ortho-chloranil (oQ). Potential of FRE is stable with time and may be used as a reference electrode in concentrated HF media without junction potential. The variation of equilibrium potential of the interface Fc¯/ Fc + at various concentrations of Fc + (10 -4 - 2 10 -2 M) obeyed to the Nernst equation with a slope 0.059 Volt per decade.