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C4-OP: LEAD DETECTION IN MILK BY MEANS OF DISPOSABLE ELECTROCHEMICAL SENSOR
F. Arduini (1), J. Quintana Calvo (1), A. Amine (2), G. Palleschi (1), D. Moscone (1)
1 Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata,
Via della Ricerca Scientifica, 00133 Rome, Italy (fabiana.arduini@uniroma2.it)
2 Faculté des Sciences et Techniques, B.P.146, Mohammadia, Morocco
Milk is a very complex food given that over 100,000 different molecular species are present and it contains almost all nutrients necessary for life. Milk, in fact, is the only food of newborn babies, but general human beings continue some milk intake during the entire life cycle, because it is a good source of many essential elements.
All 22 macro- and microelements considered to be essential to the human diet are present in milk. While several of the trace metals such as Cu and Zn have essential functions for living organisms, others, such as Cd, Hg, Pb, As, are toxic, according to the present state of knowledge. Concerning Pb, the European Union, with Regulation No. 1881/2006, fixed a maximum level in milk equal to 20 ppb. There is, then, the necessity of fast and sensitive analytical methods that would allow for daily control of toxic metal presence in milk and dairy products.
Heavy metals in milk are generally measured by atomic absorption spectroscopy (AAS), inductively coupled argon plasma spectroscopy, or mass spectrometry (MS), but voltammetric techniques also offer good possibilities. Still, very few papers devoted to the electrochemical analysis of these metals in milk can be found in the literature, and the all of these papers report the use mercury working electrodes (HMDE or mercury film electrodes) [1-3].
In this work we present the results obtained in the frame of European project Biocop (www.biocop.org) about the development of novel analytical method for lead detection in milk using a disposable environmental friendly bismuth electrode. For this purpose, we have developed milk pretreatment by means of wet digestion with HCl, HClO4 and H2O2 combined with ultrasonic. The lead detection in the milk treated is thus carried out with disposable screen printed electrode modified with Nafion and a bismuth film in anodic stripping voltammetry mode. The validation of the electrochemical lead measurement in standard solution and in milk was carried out obtaining satisfactory results. In this way, the analytical method developed allows detecting milk contaminated with lead at concentration higher than 20 ppb (legal limit) and it can be proposed as screening method for lead routine analysis in milk with the advantage to require inexpensive instrumentation.
References
- E. Muñoz, S. Palmero, Food. Control., 2004, 15, 635-641.
- R. Inam, G. Somer, Food. Chem., 2000, 69, 345-350.
- I. Karadjova, S. Girousi, E. Iliadou, I. Stratis, Mikrochim. Acta, 2000, 134, 185-191.
