The accuracy with which a date can be established is limited by uncertainties in determining the radiological dose received by the sample since it was last heated. Among the factors con-tributing to this uncertainty are: difficulty in establishing the amounts of uranium and thorium at a level of a few ppm and in establishing the degree of equilibrium following loss of radon from the sample. Proton-induced x-ray fluorescence was applied for the analyses of thorium and uranium. First results suggest that it is not sensitive enough for typical TL-dating samples. -- AATA