In this article, Laplace transform and new perturbation methods are adopted to study the problem of the chemical kinetics problem. This article presents a new evaluation procedure of 2-D fluorescence spectra obtained during a yeast cultivation without performing a calibration measurement. The 2-D fluorescence spectra are used to predict the process variables biomass, glucose and ethanol. The new calibration procedure uses a mathematical model of these process variables, i.e., differential equations, to replace any calibration measurement. The mathematical model parameters are identified simultaneously during the calculation of the chemometric models. The approximate analytical solution of the concentration biomass, glucose and ethanol compared with numerical results.