Isotope analyses boron

A. Deyhle. Improvements of Boron Isotope Analysis by Positive Thermal Ionization Mass Spectrometry Using Static Multicollection of CS2BO2 Ions. Int. J. Mass Spectrom., 206(2001) 79-89. 

Since boron concentrations in mantle minerals are exceedingly low, boron isotope analysis of mantle minerals are very restricted. On the basis of a boron budget between mantle and crust, Chaussidon and Marty (1995) conclnded that the primitive mantle had a 5 B-value of-10 2%c.ForMORB Spivack and Edmond (1987) and Chaussidon and Marty (1995) reported a 5 B-value of aronnd -4%c. Higher and lower 5 B-values observed in some ocean island basalts shonld be due to crustal assimilation (Tanaka and Nakamura 2005). 

Sweeney RE, Kaplan IR (1980) Natural abundance of as a source indicator for near-shore marine sedimentary and dissolved nitrogen. Mar Chem 9 81-94 Sweeney RE, Liu KK, Kaplan IR (1978) Oceanic nitrogen isotopes and their use in determining the source of sedimentary nitrogen. In Robinson BW (ed.) DSIR Bull 220 9-26 Swihart GH (1996) Instrumental techniques for boron isotope analysis. Rev Miner 33 845-862 Swihart GH, Moore PB (1989) A reconnaissance of the boron isotopic composition of tourmaline. Geochim Cosmochim Acta 53 911-916... 

Hemming, N.G., Hanson, G.N. 1994. A procedure for the isotopic analysis of boron by negative thermal ionization mass spectrometry. Chemical Geology 114 147-156. 

Nakamura E., Ishikawa T., Birck J. L. and Allegre C. J. (1992) Precise boron isotopic analysis of natural rock samples using a boron mannitol complex. Chem. Geol. 94, 193 -204. 

Such an approach, termed LIBS-MLIF, may be very effective in certain cases, both for analytical purposes and for isotopic analysis. For example, recently laser-ablation molecular isotopic spectrometry (LAMIS) was proposed for boron isotope analysis (Russo et al. 2011 Mao et al. 2011). LIBS-MLIF was tested for this task and proved that an easy and confident detection of different boron isotopes using well known molecular emissions (MulUken 1925) is possible. Spectra of metallic boron with a natural concentration ratio of 4 between B and B isotopes were compared with corresponding spectra of an enriched boron sample with B isotope concentration more than 96 %. MLIF (0,n= 1,2...) transitions in the system for both samples were excited at the (0,0) transition at 233.13 and at 233.19 nm for BO molecules and molecules, respectively. Both isotopes have been found in boron bearing mineral, while under both excitations, the B isotope-enriched sample exhibited typical molecular emission bands characteristic for BO molecules and B molecular emission was not fotmd (Fig. 6.10)... 

Leeman, W. P. Vocke, R. D. Beaiy, E. S. Paulsen, P. J. Precise boron isotopic analysis of aqueous samples Ion exchange extraction and mass spectrometry. Geochim. Cosmochim. Acta 1991,55, 3901-3907. 

PIGE is a rapid, non-destructive technique that is employed in the analysis of light elements such as lithium (10-100 ppm limit of detection), boron (500-1000 ppm limit of detection), and fluorine (1-10 ppm limit of detection), which are often difficult to determine by other analytical means. Because the technique is based upon specific nuclear reactions, the sensitivity of PIGE varies greatly from isotope to isotope, and this non-uniformity of sensitivity has limited its widespread use as a complementary technique to micro-PIXE. 

Isotopes in interstellar gas With the aid of the Hubble Space Telescope it has been possible for the first time to measure the boron isotopic ratio within diffuse clouds of the Milky Way. The interstellar ultraviolet radiation renders B ionized (B+) in the diffuse clouds therefore its spectrum is similar to that of the element Be, but at shorter wavelengths. The strongest resonance line lies in the ultraviolet, visible to Hubble spectrometers. The smaller mass of the 10B isotope shifts its line by 0.013 A (about 0.001%) toward longer wavelengths. Very detailed analysis of the line pair has shown in several clouds that today s interstellar abundance ratio is UB/ 10B = 3.4 0.7, which is consistent with the solar ratio 4.05. For the first time one can conclude that the solar ratio is not an abnormal one, but is shared by interstellar gas at a value larger than the ratio 2.5 that is produced by cosmic-ray collisions in the interstellar gas. Another source of11B is needed. 

Isotopic substitution may help us to obtain rotation constants. It also allows us to define atom positions within a molecule precisely (the effect of change of mass is small if the substituted atom is close to the center of mass, and zero if it is at the center of mass, for example, the rotation constants of BCI3 are unaffected by the boron isotopic mass), and may confirm the presence of a particular type of atom in the molecnle. This latter point is of particular value in studying unstable species where elemental analysis is impracticable. For example, in order to prove that a species under investigation is an oxide we may observe a shift in the position of rotational lines when 0 replaces 0. 

The technique involves the use of an inductively coupled plasma to convert trace elements to their gaseous ions followed by analysis of these ions by mass spectrometry. Examples include the quantitative analysis of trace copper by isotope dilution and the analysis of trace contaminants in boron, indium phosphide and reagent acids. 

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