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Open AccessCommunication
Chemosensors 2014, 2(4), 251-266; doi:10.3390/chemosensors2040251

Voltammetric Electronic Tongue for Discrimination of Milk Adulterated with Urea, Formaldehyde and Melamine

Instituto de Química, Universidade de São Paulo, São Paulo 05508-000, SP, Brazil
These authors contributed equally to this work.
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Author to whom correspondence should be addressed.
Received: 29 August 2014 / Revised: 16 October 2014 / Accepted: 27 October 2014 / Published: 14 November 2014
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Abstract

We report the fabrication of a voltammetric electronic tongue for the detection and discrimination of harmful substances intentionally added to milk to increase its shelf life or imitate protein content. The electronic tongue consisted of three working electrodes composed of platinum, gold, and copper. The measurement principles involved the extraction of information from cyclic voltammograms recorded in unadulterated and adulterated milk. The extracted data were analysed using principal component analysis and the contaminants were successfully differentiated from one another in a score plot. Electrochemical quartz crystal microbalance analysis was used to investigate the electrode response in order to understand the mechanism by which the tongue could discriminate between the samples. It was found that the electrochemical formation and dissolution of platinum and gold oxides, and the reduction of a copper-melamine ionic pair formed at the surface of the copper electrode were the main factors responsible for discrimination. In addition, the electronic tongue was capable of identifying adulterations in different types of milk (whole, skimmed, and semi-skimmed) and milk from different brands. The lowest concentration of adulterant that resulted in a good discrimination was 10.0, 4.16, and 0.95 mmol·L−1 for formaldehyde, urea, and melamine, respectively. View Full-Text
Keywords: milk adulteration; food adulteration; principal component analysis; hierarchical cluster analysis; sample discrimination; voltammetric electronic tongue milk adulteration; food adulteration; principal component analysis; hierarchical cluster analysis; sample discrimination; voltammetric electronic tongue
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Bueno, L.; de Araujo, W.R.; Salles, M.O.; Kussuda, M.Y.; Paixão, T.R.L.C. Voltammetric Electronic Tongue for Discrimination of Milk Adulterated with Urea, Formaldehyde and Melamine. Chemosensors 2014, 2, 251-266.

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