The validation of Kayzero-assisted NAA in Budapest, Řež, and Ljubljana via the analysis of three BCR certified reference materials

After installation and calibration of k₀-assisted NAA in three Central European research institutes (AEKI-Budapest, NPI-?e?, and IJS, Ljubljana), its validation was established via the analysis of three BCR certified reference materials. The matrices of choice were: CRM 277 estuarine sediment, CRM 038 coal fly ash from pulverized coal, and CRM 101 spruce needles. For some elements, e.g. Zn, Cd, and Hg, the analyses were not only performed instrumentally (INAA), but also in the radiochemical mode (RNAA). The work was performed in the framework of a European Copernicus Project.     

Synthesis of (purin-6-yl)methylphosphonate bases and nucleosides

Three approaches to the synthesis of the title (purin-6-yl)methylphosphonates were investigated and compared. While, the Arbuzov reaction of 6-(iodomethyl)purines with triethyl phosphite did not work, Michaelis-Becker alkylation of the sodium salt of diethyl phosphonate with 6-(mesyloxymethyl)purines gave the desired products in good yields. The best method was based on Rh- or Pd-catalyzed cross-coupling reactions of 6-iodopurines with (diisopropoxyphosphorylmethyl)zinc bromide. In this way a small series of 6-(diisopropoxyphosphorylmethyl)purine bases and nucleosides was prepared in high yields.