Mixed-valent ruthenium oxide - ruthenium cyanide inorganic film on glassy carbon electrodes as an amperometric sensor of aliphatic alcohols

A mixed-valent ruthenium oxide-ruthenium cyanide film on glassy carbon (GC/mvRuO-RuCN) electrode exhibits excellent electrocatalytic activity toward oxidation of simple aliphatic alcohols and polyhydric compounds in acidic media. Electrochemical formation of the ruthenium oxide-based chemically modified electrode can be accomplished by potential cycling or potentiostatic control in diluted sulfuric acid solutions. The attractive electrooxidation capabilities of hydroxyl-containing compounds at this modified electrode are highlighted in terms of sensitivity, stability, and catalytic action. Remarkably, the molar response of the catalytic oxidation increases on increasing the chain length of aliphatic alcohols. For example, the molar response ratio between 1-butanol and methanol is 37 in 25 mM sulfuric acid. Chromatographic separations with electrochemical detection using the GC/mvRuO-RuCN modified electrode allo rr very simple quantitation of aliphatic alcohols in real samples with linear calibration plots over about 3 orders of magnitude. The detection limits for ethanol, 1-propanol, 1-butanol, and 1-pentanol are 4, 0.8, 1, and 2 nmol injected (S/N = 3), respectively.