In this study, we compared affinity data from surface plasmon resonance (SPR) and weak affinity chromatography (WAC), two established techniques for determination of weak affinity (mM-mu M) small molecule-protein interactions. In the current comparison, thrombin was used as target protein. In WAC the affinity constant (K-D) was determined from retention times, and in SPR it was determined by Langmuir isotherm fitting of steady-state responses. Results indicate a strong correlation between the two methods (R-2 = 0.995, P < 0.0001). (C) 2014 Elsevier Inc. All rights reserved.