STATIC MULTICOLLECTION OF CS2BO2-SPECTROMETRY( IONS FOR PRECISE BORONISOTOPE ANALYSIS WITH POSITIVE THERMAL IONIZATION MASS)

Static multicollection of Cs2BO2+ ions (m/z = 308 and 309) for precise boron isotope analysis has been established by employing a newly deve loped double collector package in the modified Finnigan-MAT 261 therma l ionization mass spectrometer (TIMS). This method reduces the data ac quisition time to 5 min which is approximately one order of magnitude shorter than conventional peak jumping method, and it is easier to mea sure small sample size as low as 0.1 mu g of boron. The analytical pre cision for individual runs and reproducibility of measured B-11/B-10 r atios of NBS 951 boric acid with static multicollection, respectively, are +/- 0.007-0.025% (2 sigma(mean)) and +/- 0.012% (2 sigma(mean)), for 1 mu g of B, and +/- 0.015-0.032% (2 sigma(mean)) and +/- 0.023% ( 2 sigma(mean)), for 0.1 mu g of B. This analytical precision and repro ducibility are essentially identical to those previous works with peak jumping method measuring sample amounts more than 1 mu g of B. (Int J Mass Spectrom 176 (1998) 13-21) (C) 1998 Elsevier Science B.V.