The article studies the problem of constructing a system mathematical model of the differential inversion signal to determine the concentrations of chemical elements in multicomponent signals when measuring the ecological state of environmental objects using electrochemical methods of inversion chronopotentiometry. Using the least squares method, a mathematical model of measurement signals was obtained that allows more accurate determination of trace concentrations of toxic elements. For this purpose, the inversion signal coordinate systems were changed, an intensity signal was constructed as a transformed differential inversion signal, the baseline model of the background discharge of electrodes was built, the spectrum of the inversion components of elements was formed, models of the component signals were introduced and the inversion time was determined for calculating concentrations by the method of adding standard ion samples. The developed mathematical model was tested, which showed that the application of the model is adequate: it does not distort the integral characteristics and the obtained values of the concentrations of chemical elements. The relative error in determining the zinc concentrations in a standard solution using the mathematical and test models is 2.7%, which is acceptable in engineering calculations. The developed mathematical model of the differential inversion signal can be used when developing analytical instruments with an automated software system for processing electrochemical data.