1. Polymer-Analysis Group, Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV, Amsterdam, The Netherlands, Department of Analytical Chemistry, Universitat de Barcelona, Avda. Diagonal 647, 08028, Barcelona, Spain, and Life Science and Chemical Analysis, Pharmaceutical Solutions, Agilent Technologies, D 76337 Waldbronn, Germany