A method is presented to determine the total metallic primary zero loss (PZL) intensity and the total oxidic PZL intensity for each core-electron level in measured electron emission spectra of bare and oxidised free-electron like metals land semiconductors like Si and Gel, from the resolved PZL intensity of only the corresponding metallic main peak and the corresponding oxidic main peak, respectively. The contribution of the intrinsic plasmon structure, associated with a core level metallic main peak, to the corresponding total metallic PZL intensity is taken into account using the intrinsic bulk (BP) and surface (SP) plasmon excitation probabilities for the concerned core level electron emission process in the metal. The total oxidic PZL intensity, as given fully by the intensity of the oxidic main peak, is obtained from the measured spectrum of the oxidised metal after subtraction of a reconstructed metallic main peak. Additionally, as demonstrated for the Al 2p photoemission process in the Al metal, values for the intrinsic BP and SP excitation probabilities concerned can be determined separately from the intensities of the metallic and oxidic main peaks as obtained from a series of measured photoelectron spectra recorded from the bare metal substrate and the metal substrate covered with a thin oxide overlayer of which the thickness is varied.