METHOD OF DETERMINATION OF BORON TRIFLUORIDE ISOTOPE COMPOSITION

摘要

FIELD: analytical and radiochemistry. SUBSTANCE: method involves sampling BF₃ of natural isotope composition into glass ampoule by sorption with preliminary heated evacuated carbon BAU, SKT, SKT-2, SKT-2B, SKT-3, SKT-4A, SKT-6A, SKT-7, AT-3. Carbon is heated at T_d = 573 K and P_d = 1.3 x 10^-4 Pa. Sorption of BF₃ is carried out under atmospheric pressure and room temperature. Into other glass ampoule the preliminary prepared ether solution of Grignard reagent is placed. Both ampoules and the third ampoule also used for trimethylboron receiving are connected with vacuum unit. Grignard reagent ether solution is frozen and evacuated. Then desorption of BF₃ from carbon is carried out by heating the first ampoule to T_h = 673 K at P_h = 0.031 MPa. Grignard reagent solution is heated to the room temperature and BF₃ and Grignard reagent are interacted to yield trimethylboron. Synthesized trimethylboron is collected into the third ampoule and transferred in mass-spectrometer. Trimethylboron mass-spectrum is recorded and its isotope composition is determined by ratio of intensity of peaks of ¹⁰B⁺ and ¹¹B⁺. Transfer value of BF₃ to trimethylboron is 99%, not less. Isotope composition corresponds to the reference value for the natural composition: 19 ± 0.2 at.% of B-10 and 80 ± 0.2 at.% of B-11. Invention can be used in preparation and separation of boron isotopes and control of nuclear reactor exploitation. EFFECT: improved method of isotope composition assay. 4 cl, 11 ex