Modified carbon paste electrodes for discrimination of vegetable oils

A new methodology for the analysis of alimentary vegetable oils has been developed. Vegetables oils have been used as electroactive binder material of carbon paste electrodes. The electrochemical response of such electrodes immersed in a variety of electrolytic aqueous solutions has been exploited to discriminate the oils. The features observed in the voltammograrns are a reflect of the redox properties of the electroactive compounds (mainly antioxidants) present in the oils inside of the carbon paste matrix. The different content in polyphenols allows olive oils to be easily discriminated from sunflower oil or corn oil. Moreover, the voltammograms are strongly influenced by the pH and by the nature of ions present in the electrolytic solutions where the electrodes are immersed. As a result, each type of oil can provide a variety of characteristic signals that can be used as the input variable of a principal component analysis (PCA). The results indicate that this method allows a clear discrimination among oils from different vegetal origins and also allows olive oils of different quality (extra virgin, virgin, lampante and refined olive oil) to be discriminated. (c) 2005 Elsevier B.V. All rights reserved.