1. Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Via Amendola 165/A, I-70126, University of Bari, Bari, Italy, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium, Istituto di Metodologie per l'Analisi Ambientale (I.M.A.A.), C.N.R, Contrada S. Loja, I-85050, Tito Scalo (PZ), Italy, and HASYLAB at DESY, Beamline L, Notkestraat 85, D-22603, Hamburg, Germany