The supersymmetric model within the interacting boson model IBM4 with spin and isospin quantum numbers has been applied in our previous papers to the interpretation of energy levels and electromagnetic E2 transitions. The application of the model supersymmetric Hamiltonian to the binding energy calculations leads to the approximate mass formula with a relatively small number of parameters. The results when compared with experimental data are quite satisfactory, although not so good as extended shell model results. There is, however, another aim of this paper, namely to present an additional argument for the main assumption: the supersymmetry of the sd shell nuclei.