The unrestricted generalized transition-state model using a gradient-corrected density functional was shown in previous papers to be a reliable procedure for calculating core-electron binding energies. Relativistic corrections were estimated. Recently, a more efficient basis was proposed and tested. The results indicated that the new scaled polarized valence triple-zeta basis performs as well as the much larger cc-pV5Z basis set. This procedure is followed in the present study of the known isomers of C3H6O, C3H3NO, and C6H6. The results demonstrate that x-ray photoelectron spectroscopy, complemented by accurate theoretical calculations, can indeed be used to help chemical analysis.