Studies on the isotopic analysis of boron by thermal ionisation mass spectrometry using NaCl for the formation of Na2BO2+ species

Studies were carried out on the use of NaCl instead of sodium carbonate or sodium hydroxide for the formation of Na2BO2+ ion used for the determination of isotopic composition of boron by TIMS. The addition of mannitol which forms an anionic complex with boron was found to be essential when using NaCl. The investigations show that when NaCl is used, B/Na molar concentration ratio need not be critically adjusted to 1 as required in case of sodium carbonate or sodium hydroxide. The B-10/(11) B ratio was found to be independent of B/Na molar concentration ratio in the range of 25-0.05. This aspect is extremely useful in carrying out isotopic analysis of B in unknown samples solutions. NIST boron isotopic standard SRM-951 having B-10/(11) B isotopic ratio of 0.2473 +/- 0.0002 was used in these studies and a value of 0.24742 +/- 0.00006 (1 sigma) was obtained. (C) 2008 Elsevier B.V. All rights reserved.