A PRELIMINARY VOLTAMMETRIC STUDY OF SILVER IONS IN LIPOPHILIC FOOD SIMULANT

A PRELIMINARY VOLTAMMETRIC STUDY OF SILVER IONS IN LIPOPHILIC FOOD SIMULANT C. Titton, F. Felician, M.A. Baldo, S.Fabris, S. Daniele Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari, Via Torino, 155 – 30172 Venezia Mestre Recently, nanomaterials (NMs) have gained increasing popularity in the food industry, particularly for product preservation and food packaging, as their use can improve the thermal and mechanical resistance of products and, above all, imparts antimicrobial properties to packaging [1]. In this context, silver nanoparticles occupy a primary place thanks to their well-known activity, mainly attributed to ionic silver form, against a wide variety of both Gram-positive and Gram-negative bacteria. However, silver species, especially soluble Ag(I) ions, could be released from such products into food matrices and this could pose risks to human health. Therefore, studies concerning their migration from food packaging to the external environment have become necessary. Investigation on Ag(I) release typically involves contacting the test materials with fluids that simulate the physico-chemical properties of food, and then detecting the amount of Ag species released. According to the European Commission, for aqueous and semi-fatty foods, suitable fluids as food simulants are water solutions and water/ethanol mixtures, while, for fatty products, vegetable oils are indicated as lipophilic simulants [1]. Quantification of silver species released in food simulants are in general performed by spectroscopic techniques, providing total silver detection. Instead, to distinguish between ionic silver from other forms in liquid media, electrochemical approaches are more suited. In the literature, only a few voltammetric investigations on Ag(I) ions release in food simulants with a high-water content have been reported, while, to the best of our knowledge, no report exists on the migration of Ag(I) ions in lipophilic food simulants. Accordingly, in this study we investigated on the voltammetric behavior of Ag(I) ions in a lipophilic simulant made by olive oil mixed with the ionic liquid [P14,6,6,6][NTf2], which is known to be soluble in vegetable oils and act as supporting electrolyte [2]. Sets of measurements were performed, using a microdisk electrode, at temperatures ranging from 25 to 40 °C, i.e. the interval normally used for migration tests of species from food packaging. Under these conditions, the diffusive parameters of Ag(I) ions were studied to define mass transport characteristics of the species in the test media, as they are fundamental for the definition of analytical quantification protocols. [1] EEC Regulation No 10/2011, https://eur-lex.europa.eu/eli/reg/2011/10/oj [2] P.Oliveri, M.A.Baldo, S.Daniele, M.Forina, Anal. Bioanal. Chem., 395 (2009) 1134-1143.