Publication Type:Journal Article
Source:Geostandards and Geoanalytical Research, Wiley-Blackwell on behalf of the International Association of Geoanalysts, Vandoeuvre-les-Nancy, France, Volume 33, Number 2, p.169-181 (2009)
Keywords:accuracy, actinides, anions, inductively coupled plasma methods, instruments, ion exchange, isotope dilution, Isotopes, Lead, mass spectroscopy, measurement, metals, reagents, sample preparation, spectroscopy, techniques, thorium, U/Th/Pb, Uranium
A comparison between HBr-HCl and HBr-HNO (sub 3) based anion chemistry is presented to test the efficiency of Pb purification in the preparation of samples for isotope ratio measurement by ICP-MS. It was found that the small advantages in yield and blank offered by the HNO (sub 3) -based method were more than compensated by the more effective matrix removal of the HCl-based method. Apart from very zinc rich matrices (e.g., sphalerite), a careful single pass purification using HBr and HCl removed more than 99.9% of the matrix. In preparation for the isotope ratio analysis, a small (2-5% m/v) liquid sample aliquot was analysed to determine U, Th and Pb concentrations by solution quadrupole ICP-MS. This allowed accurate prediction of the expected ion signal and permitted optimal spiking with Tl, if desired, for mass bias correction. Long-term results for international rock reference materials showed reproducibilities of better than 1% (Th/U) and 1.5% (U/Pb). For most geological applications, such analyses obviate the need for isotope dilution concentration measurements. Abstract Copyright (2009), International Association of Geoanalysts.
GeoRef, Copyright 2018, American Geological Institute.<br/>2012-082973<br/>quadrupole mass spectroscopy