Quantification of Calcium, Phosphorus, and Cerium in Novel Biocompatible Materials by Total Reflection X-Ray Fluorescence Spectroscopy

Abstract

An approach to determining the composition of new biocompatible materials based on cerium-containing calcium phosphates using the TXRF method is proposed. The ranges of analyte contents in solutions were determined for the correct determination of Ca, P, and Ce using the external reference method. A systematic underestimation of the calcium signal was noted when its content in the analyzed composite sample was above 30 mg/L. In order to assess the compliance of the sample with the thin layer criterion, an analysis of the Compton scattering spectra for the ceramic sample solution was carried out; the maximum value was 16.8 keV (96°). According to the plot of the mass attenuation coefficient for a film of a given composition, the attenuation of the intensity of the calcium line perpendicular to the substrate is not associated with absorption of the sample. Internal reference samples (Gd and Cu) were selected and conditions were found for determining micro- and macrocomponents in solutions and suspensions of samples. It has been shown that, when the calcium content in the sample is up to 50 mg/L, it is possible to correctly determine Ca, P, and Ce using the TXRF method in solutions and suspensions with S_r of 0.05 and 0.09, respectively. The convergence of the results obtained using the external and internal reference methods with appropriate dilutions of solutions and suspensions was noted.