The publication considers the modifying effect of refractory zirconium carbide in determining elements by hydride generation atomic absorption spectrometry. It is shown that the nature of binding of atoms of the analytes consists in the ability of the ZrC surface to strong adsorption. For As, Cd, Pb, Sb, Se, Te elements the adsorption energies of atoms on the ZrC(100) surface are calculated by the density functional theory. It is found that the necessary condition for adsorption is the preliminary cleaning of the ZrC surface from chemisorbed hydrogen. Correlation is demonstrated between the pyrolysis temperature that is maximum achievable for the analyte in the specimen with the adsorption energy of its atomic form on the ZrC(100) surface.