The binding energies of 1s-, 2p-, 3d- and 4f-states of a spherical quantum dot (QD) with parabolic potential are investigated by using the perturbation method. The binding energies are calculated as a function of impurity position. The results show that the dot radius and the parabolic potential have a great effect on the binding energies and there is a linear relationship between the dot radius and impurity shift corresponding to the binding energy maximum. In addition, the binding energies show a strong dependence on the impurity position within the dot. While the binding energies for s-state have the maxima for an on-center impurity case, the binding energy maxima of the p-, d- and f-states take place at different points between the center and edge of the dot. © 2013 Elsevier Ltd. All rights reserved.