Applications of transfer function to derivation of a high precision model of tracer flow in a commercial measurement system is presented. A transfer function concept makes easier development of models of complex systems and consequently allows for obtaining a model that matches in the best way a physical system. The method has an additional profit viz. the same numerical algorithm i.e. inverse Laplace transform can be employed to solve the model both on the stage of precise model development (boundary value problem) and to find real model parameters (inverse boundary value problem). As a result of concept application, a very precise model of commercial measurement instrument was developed and, next, it was employed to determination of axial dispersion coefficients for empty tube and packed bed. Presented method is precise in wide range of operating conditions and faster comparing to other methods previously described in literature. The paper shows that mathematical modelling can be exploited to enhance measurements for a commercial measurement instrument i.e unlock the full potential of the commercial measurement system with no equipment design changes. The method is also a fast alternative to computational fluid dynamics for high precision calculations.