1. Institute of Chemistry, University of Neuchâtel, Avenue Bellevaux 51, CP 158,2009 Neuchâtel, Switzerland, Laboratory of Chemometrics, National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia, and Département de Chimie Moléculaire UMR 5250, ICMG FR 2607, CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France