Analytical control of Mn and Se in synthesized compounds, promising plant-derived medicines, by WDXRF and TXRF methods

Some organic compounds extracted from plants serve as raw materials to synthesize new drugs. Quantification of the metal or semimetal bound with the organic molecule, and the control of foreign elements are very important to ensure the quality of the future medicinal products. In the synthesized compounds of Mn with dihydroquercetin (Mn-DHQ) and Se with arabinogalactan (Se-AG), it was required to determine the content of Mn and Se. The authors of the paper applied wavelength-dispersive (WDXRF) and total-reflection (TXRF) X-ray fluorescence methods to quantify above elements. In absence of suitable certified reference materials, the synthetic samples were prepared for calibration of WDXRF spectrometer. Two sample preparation procedures were used in the TXRF: acid digestion and dissolution by water. The Mn contents in compounds with DHQ amounted to 13.5–17.4% by WDXRF and 13.1–18.2% by TXRF. The Se contents in compounds with AG did to 0.5–12.9% and 0.5–13.6%, respectively. Statistical data processing did not reveal a significant difference between the results of two methods. To check the foreign elements in the synthesized substances the X-ray spectra were recorded. Some minor peaks in the energy range of 5.9–7.5 keV were found on TXRF spectrum of the Se-AG sample as the consequence of its contamination. The Mn complexes did not contain any foreign elements. Additionally, determined element contents were compared with ones calculated through chemical formulas of resulting compounds to characterize their cleaning level from impurities. [Display omitted] •Two XRF methods were developed for analysis of medicines.•Mn and Se contents were quantified by XRF without CRMs.•The synthetic samples were prepared for calibration and trueness control.•Acid digestion and water dissolution were applied for TXRF analysis.•X-ray spectra were used to control the purity of samples.