Compensation of Roentgen Exciting System Instability in Conducting X-Ray Fluorescence Analysis of Bioassays

Detailed analysis of the backscattering peak in the X-ray fluorescence spectrum was carried out using the Monte Carlo method which is the base of the computer code "SNEGMONT" for simulating the transport of electrons and photons. The calculations show that the intensity of the backscattering peak is directly proportional to the intensity of the exciting radiation. It was found that the intensity of analyzed elements' lines has a strict relation with the intensity of the backscattering peak. The example of determination of lead and zinc concentrations in bioassay is presented. The simulation of an eightfold change of the exciting X-rays intensity which taking into account the obtained strict relation allows to determine the true concentration of elements with an error of no more than 3%.