Development of a voltammetric electronic tongue for discrimination of edible oils

In this paper we propose a novel strategy to perform cyclic voltammetric measurements with a platinum microelectrode directly in edible oil samples. The microelectrode was employed as an electronic tongue which, along with the application of chemometrics to the current-potential responses, proved useful for discriminating oils on the basis of their quality and geographical origin. The method proposed here is based on the use of suitable room temperature ionic liquids added to oils as supporting electrolytes to provide conductivity to the low-polarity samples. In particular, it was shown that the addition of 0.1M trihexyl(tetradecyl)phosphonium decanoate or trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide to maize and olive oils provided sufficient conductivity to allow cyclic voltammograms to be recorded at a platinum microelectrode. The voltammograms, considered as fingerprints of the oil samples, were processed via Principal Component Analysis. Data processing showed that oils having different nature (i.e. maize and olive) or geographical origin (i.e. olive oils coming from different regions) can be distinguished.