1. Analytical Chemistry Department, University of Barcelona, Barcelona, Spain
2. Conservació Preventiva i Restauracio, Fundació Museu Picasso, Barcelona, Spain
3. Istituto di Scienze e Tecnologie Molecolari (CNR-ISTM), Perugia Unit, Italy
4. SMAArt Center, University of Perugia, Perugia, Italy
5. Istituto Nazionale di Ottica (CNR-INO), Florence, Italy