High precision lead isotope ratio measurements by multicollector-ICP-MS in variable matrices

It is well known that the use of thallium as an internal standard for high precision and high accuracy measurement of lead isotopic ratios can correct for mass discrimination and instrumental drift. The present work demonstrates that matrix effects can also be accounted for when a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) is used. The precision (2 sigma) obtained for the Pb-207/Pb-206 and Pb-208/Pb-206 ratios was 30 and 40 ppm, respectively, even in samples with total dissolved solid (TDS) levels of up to 700 mg L-1.