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

Author(s)

Bueno, Ligia ; de Araujo, William R. ; Salles, Maiara O. ; Kussuda, Marcos Y. ; Paixao, Thiago R. L. C.

• Document type: Journal article
• Source: CHEMOSENSORS; v. 2, n. 4, p. 16-pg., 2014-12-01.

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. (AU)

• FAPESP's process: 12/12106-5 - Development of intelligent devices (electronic noses and tongues) using electrochemical, colorimetric and mass measurements aiming to the discrimination of forensic and food samples
• Grantee: Thiago Regis Longo Cesar da Paixão
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/23355-3 - Study and development of intelligent devices (electronic noses and tongues) aiming to the discrimination of contamination in foods
• Grantee: Lígia Bueno Bedatty
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 11/11115-8 - Development of a hibrid tongue (electrochemistry and colorimetric) aiming the discrimination of forensic samples.
• Grantee: Maiara Oliveira Salles
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 11/19903-5 - Development of electroanalytical methods for detection/discrimination of drugs of abuse, its adulterants and explosives in forensic samples
• Grantee: William Reis de Araujo
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)