A new experimental technique, employing a continuous stirred-tank reactor, for studying enzyme kinetics in the presence of inhibitor-contaminated substrate is described. The proposed method is simulated mathematically for competitive, uncompetitive, and mixed-type noncompetitive inhibition. The step-by-step experimental procedure is described, as is the necessary data analysis for determining the kinetic parameters. Differences in system response for enzyme inhibition by excess substrate and by an impurity are illustrated, and a stability analysis of the system is performed.