Sensitivity And High-Precision Lead Isotopic Analysis By Multicollector Inductively Coupled Plasma Mass Spectrometry Based On Liquid Spray Dielectric Barrier Discharge Plasma-Induced Chemical Vapor Generation

In this study, a simple but highly sensitive and cost-effective lead isotopic analysis strategy is presented. The design uses liquid spray dielectric barrier discharge plasma-induced chemical vapor generation (LSDBD-CVG) coupled with multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). In this LSDBD-CVG approach, Pb was efficiently converted into volatile species in the presence of 1% (v/v) formic acid, which enhances the signal more than seven times and thus enables high-precision Pb isotopic analysis even at low concentrations. The minimum Pb required per analysis with LSDBD-CVG is similar to 16 ng, which is one order of magnitude less than the amount needed for the pneumatic nebulization sample introduction. Pb isotopic fractionation during LSDBD-CVG was observed, but the mass bias could be effectively corrected using Tl-205/Tl-203 correction combined with standard-sample bracketing. Under optimized conditions, the external precisions at 20 mu g L-1 of Pb with 8 min acquisition time for Pb-208/Pb-204, Pb-207/Pb-204, and Pb-206/Pb-204 were found to be 35, 90, and 23 ppm (2RSD), respectively. The methodology has been successfully validated by Pb isotopic analysis of solutions standard of NIST 981 and geological reference materials (BCR-2 and BHVO-2). Additionally, the good agreement of the measured Pb isotopic compositions of selected soils and Pb-Zn ore district materials obtained by this method with those obtained by membrane desolvation sample introduction using MC-ICPMS further demonstrates its applicability for real samples. As a green and efficient sample introduction method, LSDBD-CVG offers higher sensitivity and better tolerance of coexisting ions than wet plasma conditions for Pb isotopic analysis. Furthermore, the sampling of Pb and Tl can be achieved simultaneously in LSDBD-CVG, which greatly simplifies the introduction system compared with CVG/gas chromatography-MC-ICPMS. The proposed LSDBD-CVG provides a promising new sample introduction strategy for high-precision isotopic analysis, especially for the analysis of isotopes in microsamples.