1. International Iberian Nanotechnology Laboratory, Braga4715-330, Portugal
2. Department of Analytical Chemistry, Nutrition and Food Science, School of Veterinary Sciences, University of Santiago de Compostela, Campus of Lugo, Lugo27002, Spain
3. Department of Food Analysis and Nutrition, Faculty of Food and Biochemical Technology, University of Chemistry and Technology Prague, Prague 6, Prague166 28, Czech Republic
4. Centre of Chemistry, University of Minho, Campus de Gualtar, Braga4710-057, Portugal
5. Center of Physics of the Universities of Minho and Porto, University of Minho, Braga4710-057, Portugal