Chemical composition of internal interfaces and especially grain boundaries differs from that of the grain interior and controls materials behavior. Application of the mostly spread method of surface analysis – Auger electron spectroscopy (AES) – for measurement of nanochemistry at these buried surfaces is complicated by necessity to open the boundary by intergranular brittle fracture. Consequently, the quantification of AES spectra must also take into account redistribution of the species, segregated at the boundary, between the two fracture surfaces. In this contribution, we analyze the transformation of AES spectra onto grain boundary concentrations using the standardless methods, which are reliable for determination of thermodynamic parameters characterizing the grain boundary segregation.