High-purity copper samples were irradiated with high-energy protons and neutrons, The concentration of transmutational elements was measured by means of the total reflection x-ray fluorescence method using synchrotron radiation, The spectra of non-irradiated samples were substracted from the spectra of the irradiated samples, By this evaluation method, the minimum detectable concentration was as low as 1.5 mu g g(-1) in a copper matrix.