Photoluminescence (PL) experiments under high magnetic fields in the Faraday configuration on nitrogen-doped ZnSe epilayer structures grown by molecular beam epitaxy are applied to study the impurity centers in the compensation limit. Following the nitrogen concentration level [N], different regimes of field dependence of the donor-acceptor pair transitions are reported. The wave function shrinkage model gives the mean distance (R) between impurity centers as the critical parameter for this feature. The transitions related to excitons bound to shallow (I-1) and deep accepters (I-1(P)) are also discussed. Their field-dependences are observed to be directly connected to the nitrogen doping density, and imply different capture rates depending on the nature of the neutral impurity.