Electronic Supplementary Material (ESI) for Analytical Methods This journal is © The Royal Society of Chemistry 2013 Supplementary Information for Affinity analysis between L-arginine immobilized and plasmid isoforms provided by Surface Plasmon Resonance Carla Cruz*, A. Sousa, F. Sousa, João A. Queiroz a CICS-UBI - Centro de Investigação em Ciências da Saúde, University of Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal Figure S1- Percentage of sites occupied for L-arginine/plasmid pUC19 isoforms.