Impurity-related optical-absorption spectra for GaAs-(Ga,Al)As quantum wells under an externally applied longitudinal electric field are investigated. A variational procedure in the effective-mass approximation is used in the evaluation of the impurity binding energies and wave functions. Effects of the variation of both field intensity and well width on the donor- and acceptor-related absorption line shapes are analyzed in the cases of infinite- and finite-barrier potentials. The results show that the absorption spectra present an edge associated with the maximum value of the impurity binding energy and two van Hove-like singularities corresponding to impurities positioned at the two edges of the well. As the field intensity is increased, the absorption spectra are shifted towards lower energies, with their intensities reduced, and the relative importance of the van Hove-like singularities is changed. Such effects become more pronounced for larger widths of the quantum wells.46740414046