Background limitations in X-ray fluorescence analysis

Possibility for decreasing detection limits of heavy elements in technological solutions of nuclear fuel cycle by the X-ray fluorescence an a lysis method with previous selection according to sample radiation energy is considered. Analysis of aqueous solutions containing uranium in the amount of -1-10 μm was performed using KBKhV-7 (50 eV 70 mA) powerful X-ray tube. It is shown that the method described permits to obtain the highest values of peak backgrround relations in the case of crystal-free x-ray fluorescence analysis of thick samples. These ultimate achievable relations are determined by processes in the sample it self: photoelectron bremsstrahlung and the Compton bound-lelectron scattering. Using for excitation commercial x-ray tubes of several kilowatt power in light matrices heavy metals with a content of an order of 10-8 can be analysed