To investigate the effect of [ninhydrin] on the reaction rate, the kinetic experiments were performed at different concentrations of ninhydrin ranging from 6.0 × 10−3 to 40.0 × 10−3 mol dm−3 at constant [Gly-Tyr] (3.0 × 10−4 mol dm−3), temperature (70 °C), and pH (5.0). The rate constant values in the two media are recorded in Table 1. The rate constant vs. [ninhydrin] profile is non-linear and pass through the origin (Fig. 4); this indicates the order with respect to [ninhydrin] to be fractional in both the media.