American Journal of Applied Chemistry 2014; 2(2): 27-32 Published online April 20, 2014 (http://www.sciencepublishinggroup.com/j/ajac) doi: 10.11648/j.ajac.20140202.11 Determination of isotopic composition and concentration of uranium and boron by thermal ionization mass spectrometric isotopic dilution technique Hilal Shahab Wahab 1, * , Khalil Ibraheem Hussain 2 1 Department of chemistry, College of Science, Al-Nahrain University, Al-Jadriya, Baghdad, Iraq 2 Department of chemistry, College of Education - Ibn Al-Haitham, University of Baghdad, Al-Aadhamiya, Baghdad, Iraq Email address: hswahab@yahoo.com (H. S. Wahab) To cite this article: Hilal Shahab Wahab, Khalil Ibraheem Hussain. Determination of Isotopic Composition and Concentration of Uranium and Boron by Thermal Ionization Mass Spectrometric Isotopic Dilution Technique. American Journal of Applied Chemistry. Vol. 2, No. 2, 2014, pp. 27-32. doi: 10.11648/j.ajac.20140202.11 Abstract: In this study, the determination of isotopic composition and concentration of uranium and boron by mass spectrometric isotopic dilution have been performed .The isotopic composition was measured using thermal ionization mass spectrometer methodology employing U-233 and B-10 as spike isotope standards. The accuracy and reproducibility of the isotopic ratio and concentration measurements were evaluated. Keywords: Mass Spectrometry, Boron Isotopes, Uranium Isotopes, Isotope Dilution Technique 1. Introduction Boron and uranium are extremely important elements in the field of nuclear science researches, due to the nuclear fuel backbone of uranium and the 10 B (n,α) 7 Li neutron capture reaction [1]. Furthermore, boron is used in a primary coolant system in pressurized water reactors in the form of boric acid to control the reactivity in the core [2]. Accordingly, the precise quantification of their isotopic composition is of great interest in nuclear industry and also in environmental studies [3] .Isotope dilution technique (IDT) has been extensively employed by several authors for the determination of boron [4-7] and uranium [8-10]. The key stipulation of IDT analysis is existence of at least two stable isotopes for the element under consideration, because the method is based on the ratios of the isotopes [11-12] .This limitation, however, is somewhat less restrictive because a number of elements have artificial isotopes of long half-life which undergo negligible decay over the duration of the determination. The stable isotope dilution method can be used for the analysis of about 80% of the elements. The sensitivity of the method varies from element to another, from a few g to 10 -3 gm or even less. In step with development of mass spectrometry, Isotopic dilution technique has found widespread application in solving complicated analytical problems, in the determination of geological age, in establishing yields of fission products and conditions of radioactive splitting and in studying a number of other nuclides as burn up monitors [13-15] for the burn up determination of the isotopic composition of fissile elements in the initial and irradiated fuel or the measurement of some stable fission products which serve as burn up monitors. 2. Experimental 2.1. Apparatus Thermal ionization mass spectrometer (MAT 261), Finnegan Mat Co. (Germany) The conditions for boron isotope analysis were as follows: The applied current on evaporation and ionization filaments was 1.5-1.7 A Temperature range 750-1000 0 C Ion measured Na 2 BO 2 + Mass: 88 correspond to Na 2 B 10 O 2 + : 89 correspond to Na 2 B 11 O 2 + The currents of evaporation and ionization filaments were step wise increased (0.2A every 3 min.) so a stable and intense isotope peak of B 10 and B 11 is reached in a period of twenty minutes [16]. The experimental parameters for uranium isotopes determination were as follows: