G protein coupled receptors (GPCRs) are the targets of 30-40% of all approved drugs. However many approaches successfully applied to drug discovery for soluble protein targets have made a limited impact on GPCR’s due to challenges in obtaining pure, active, membrane free receptors for structural and biophysical investigation. Biophysical techniques in combination with improvements in protein engineering and handling have advanced to face the challenges of studying membrane bound GPCR’s with SPR in particular becoming increasingly utilized in the study of GPCR’s as the sensitivity of the detections systems has improved. Here we present the results from a collaboration with the Hopkins-Navratilova lab at the University of Dundee highlighting the importance of instrument sensitivity characterizing GPCR’s with the Biacore™ S200.