A fit-for purpose procedure for lead isotopic ratio determination in crude oil, asphaltene and kerogen samples by MC-ICPMS

作者：Ortega Georgia Sanabria; Pecheyran Christophe^*; Berail Sylvain; Donard Olivier F X

来源：Journal of Analytical Atomic Spectrometry, 2012, 27(9): 1447-1456.

DOI：10.1039/c2ja30143a

Lead isotopic ratios have been used extensively in geological, geochronological, and archaeological studies. However, the classical anion exchange method for Pb isolation/purification using AG1-X8 resin cannot be directly adopted for high content organic samples such as crude oils, due to the fact that the sample matrices probably interact with the active sites in the resin. This results in low percentages of Pb being recovered during column separation and low-level sample purity, therefore affecting the precision of the MC-ICPMS isotopic ratio. For Pb isolation/purification from crude oil samples, at least 0.5 mL of the resin AG1-X8 is required to obtain high Pb recovery without fractioning during the analysis of crude oil. After evaluation of 5 different mass bias correction methods, the combination of Tl normalisation (exponential law) and standard bracketing was selected, providing a precision of 0.0039, 0.0014 and 0.0012 and accuracies (parts per thousand) of 0.001, 0.001 and 0.004 for Pb-208/204, Pb-207/204 and Pb-206/204 isotope ratios, respectively, in the analysis of a solution of 10 ng mL(-1) SRM NIST 981 (n = 18). The proposed procedure allows the reliable determination of Pb isotope ratio in crude oil, asphaltene and kerogen samples, important in geochronological studies.

• 出版日期2012