The isobaric yield ratios of the fragments produced in the neutron-rich 48 Ca and 64 Ni projectile fragmentation are analyzed in the framework of a modified Fisher model. The correlations between the isobaric yield ratios (R) and the energy coefficients in the Weiszäcker-Beth semiclassical mass formula (the symmetry-energy term a sym , the Coulomb-energy term a c , and the pairing-energy term a p ) and the difference between the chemical potential of neutron and proton (µ n − µ p ) are investigated. Simple correlations between (µ n − µ p )/T, a c /T, a sym /T, and a p /T (where T is the temperature), and lnR are obtained. It is suggested that (µ n − µ p )/T, a c /T, a sym /T, and a p /T of neutron-rich nuclei can be extracted using isobaric yield ratios for heavy-ion collisions at intermediate energies.PACS numbers: 21.65. Cd, 21.65.Ef, 21.65.Mn, 25.70.Mn