Financial support from the Spanish Ministry of Economy and Competitiveness through Project CTQ2012-36711 (cofounded by FEDER) is acknowledged. Additional funding for a research stay of Lourdes Somoano Blanco provided by the HelmholtzZentrum Geesthacht is also acknowledged. The UE is acknowledged for the provision of FEDER funds for the purchase of the GC-MS/MS instrument. P. Rodríguez-González acknowledges his research contract RYC-2010-06644 to the Spanish Ministry of Economy and Competitiveness through the Ramón y Cajal Program.
Spanish Ministry of Economy and Competitiveness/CTQ2012-36711 Ramón y Cajal Program /RYC-2010-06644