Ferrocene reference electrode

in concentrated HNO3 solutionS


A. Benayada3, B. Hammouti1*, H. Oudda2

1 Laboratoire d'Electrochimie Analytique et Appliquée, Ecole Mohammadia d’Ingénieurs, Université Mohammed V, BP.765 Rabat Morocco 

2 LCAE-URAC18, Faculté des Sciences, Université Mohammed Premier-Oujda Morocco

Laboratoire des Procédés de Séparation, Faculté des Sciences, Université Ibn Tofail, Kenitra, Morocco

* Corresponding author: E-mail: hammoutib@gmail.com

Received: 10 October 2011; revised version accepted: 12 November 2011



     The practical reference electrode (FRE) was a carbon paste electrode (CPE) containing ferrocene (Fc¯) immersed in nitric acid solution at a given concentration of ferricinium (Fc+) ion. The advantage of this FRE is to eliminate junction potential (JP). Fc+ was prepared quantitatively in biphasic medium HF-toluene by the 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 HNO3 media. But when acidic concentration varies from diluted to concentrated solutions, the junction potential limits the use of FRE when acid concentration of analysed solution varies, but it may be prepared in each acidic medium used.


Keywords: Ferrocene; Strehlow; Concentrated acid; HNO3; Carbon paste electrode.


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