Determination of boron isotope ratios in geological materials by inductively coupled plasma mass spectrometry

Abstract

A method for the determination of B isotope ratios In a variety of geological materials Is described. Boron isotope ratios are determined with a precision of 0.7 % In materials containing as little as 0.5 ppm B. Sample material Is leached with HCI In sealed pressure tubes or fused with sodium carbonate. Separation and/or preconcentration of B from matrix elements Is accomplished by using AmberlHe XE-243, Dowex 50W-X8, or Chetex-100 resins. The use of NASS-1 reference seawater Is suggested as a reference material for calculating and comparing isotope shifts for different geological materials. Nonspectroscoplc Interferences due to the presence of concomitant elements In solution are shown to cause 11B Ion count rate suppression at concentrations of Na above 2000 ppm. The presence of excess amounts of concomitant elements causes a matrix-induced mass discrimination effect. Boron Isotope ratios (11B/10B) for the materials studied ranged from 3.91 to 4.18 for basalt and seawater samples, respectively.

Appraisal of Sims applicability to boron studies in plants

“…The mean values (Ϯ 95% confidence interval) are 0.278 Ϯ 0.010 and 0.262 Ϯ 0.054, respectively. These two values are reasonably consistent with each other and with the expected value for natural boron, which ranges from 0.236 to 0.255 in terrestrial samples (Grégoire, 1987). However, the slight excess of the measured value compared with the range of expected values may result, at least in part, from the small isotopic effect in favor of the light isotope, which is known to occur in the SIMS procedure (Slodzian, 1982).…”

Inductively coupled plasma mass spectrometry

“…Some of the results conflict with one another, so a general consensus will be presented. As shown in Figure 9, the analyte signal is generally suppressed by moderate to high concentrations of other matrix constituents (85,138,151,152,156,160,165,(175)(176)(177)(178)(179) although some enhancements of analyte signal have also been reported (95,156,159,176,177). Some of these results were obtained under typical operating conditions used for analyses.…”

“…The configuration and potentials of the ion lens elements can also greatly affect ion signals (129,138,146,150) and the accuracy of isotope ratio measurements (150,151). It is desirable to find operating conditions for which metal oxide ions are minimized and metal ion signal is maximized.…”

“…Internal standardization also can be used to compensate for a modest amount of sensitivity suppression; in this case, the analyst should verify that the internal standard signal reacts to solute levelsin the same way as that for the analyte elements (85). Generally, a good internal standard for ICP-MS work is an element which is close in mass and ionization energy to the analyte (85,151,152,159,(176)(177)(178). Beauchemin et al (156) made the excellent suggestion that background ions such as C + and AT2+ are effective internal standards and can be used to reduce the number of elements that must be added to the sample.…”

Boron isotope dilution in cellular fractions of coffee leaves Evaluated by Inductively Coupled Plasma Mass Spectrometry with direct injection nebulization (DIN-ICP-MS)

“…Evans and Krahenbuhl 7 noted a significant interference of 12 C on B when analyzing microwavedigested samples using ICP-MS in the normal resolution mode (0.8 u). In the high-resolution mode (0.6 u) Gregoire 14 reported good results for geological solutions, but not for biological digests. 17 In the present paper, intrinsic 10 B labeled coffee leaves were submitted to a sub-cellular fractionation procedure.…”