The Delplot analysis for reaction network elucidation involves the use of measured species and their yields as a function of reactant species. Highly reactive intermediates, such as free radical and other mechanistic intermediates, however, will often have large reaction rate constants relative to other species. This can cause the product classification by the Delplot technique, which uses only observable species, to be confounded. The present work addressed this issue, where the limitation of the use of the Delplot technique to classify the fleeting intermediate species was explored. To achieve this aim, the series reaction mechanism given by A ->(k1) B ->(k2) C was used to synthesize the kinetic data at various values of reaction rate constant ratios lambda = k(2)/k(1). At low lambda, it was found that kinetic data can be collected through the reaction time and the product ranks are as indicated by the mechanism. At high lambda, the Delplot analysis will disguise the reaction mechanism if the kinetic data are not collected at ultralow conversion. The present results also suggest that, during parameter estimation for the determination of kinetic parameters, no more than 2 orders of magnitude should separate the initial guesses for the reaction rate constants if all of the species in the network are observable.