Kinetic methods that are independent of the rate of reaction

Kinetic methods for the quantification of substrates offer a number of advantages over equilibrium methods, such as speed and economy. However, in their most commonly practiced form they are liable to error from various sources in addition to those ordinarily encountered in equilibrium methods, owing to variations in enzymic activity between test and standard assays. In certain circumstances the differences in enzymic activity may be such as to completely invalidate the method. Such difficulties may, however, be avoided if three or more measurements are made during the reaction of the sample and are evaluated by one of five means. In each case data from the early course of the reaction are used to predict the total change in sensor signal at infinite time, from which the concentration of the substrate may be calculated as for an equilibrium method.