Determination of stable isotope ratio of lead in airborne particulate matter by ICP-MS

Abstract

ICP-MS was applied to the measurement of stable isotope ratios of lead, which are used as an indicator of the source of lead in airborne particulate matter. For the measurement of lead isotopes ratios, the influences of machine conditions, lead concentration and matrix elements to the precision and accuracy of the measurements were studied. At a scanning mode, dwell time of 40~160 μs gave the best precision to the isotope ratio measurements; about 0.3% of R. S. D. for 206Pb/207Pb and 206Pb/208Pb, 0.6% for 206Pb/204Pb. Precision of the measurement was better at a high concentration of lead in sample solution. The observed value of 206Pb/207Pb ratio was not affected by the lead concentration, but in the cases of 206Pb/204Pb and 206Pb/208Pb, about 1 % of the value changed in the observed ratios with the lead concentration of 100~500 μg/l.matrix elements (Na, K, Ca, Mg, Al, Fe) did not affect the observed isotope ratios up to 200 mg/l. The lead isotope ratios of reference materials |Urban Particulates (NIST) and Vehicle Exhausted Particulates (NIES)| were measured by using two kinds of sample; crude sample and lead-isolated sample from matrix elements by anodic deposition. Both cases gave the same isotope ratio values, therefore, lead isotope ratios in airborne particulate samples can be measured by ICP MS without any separation of lead from matrix elements. © 1990, The Japan Society for Analytical Chemistry. All rights reserved.