Abstract
Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) enables the precise determination of mercury (Hg) isotopic compositions in different types of samples. However, isotopic measurements in samples with low Hg concentrations and small sample mass remain a challenge. In this study, we developed an optimized protocol for high precision Hg isotope determination using a modified cone arrangement (X skimmer cone + jet cone) with Neptune Plus MC-ICP-MS. Through modification of the HGX-200 continuous-flow cold-vapor generation system, and careful optimization of the instrument gas flow rates, we obtained steady and high signal sensitivity for Hg (202Hg: 1.78 V per ng mL-1). Our method allowed the precise determination of low Hg concentration in solutions (0.10 ng mL-1), which is the lowest according to the literature. Only 0.70 ng Hg in samples was required according to our new analytical method, which enables the direct measurement of low Hg concentration in samples (down to 5 ng g-1), after direct acid digestion treatment. Using our method, the Hg isotopic compositions of four igneous rock standard reference materials (BCR-2, BHVO-2, GSP-2, and GSR-2) were reported for the first time. The standard reference materials showed large variations of δ202Hg (-1.24 to -2.47‰), indicating that mass dependent fractionation (MDF) of Hg isotopes occurred during magmatic processes.
| Original language | English |
|---|---|
| Pages (from-to) | 1932-1940 |
| Number of pages | 9 |
| Journal | Journal of Analytical Atomic Spectrometry |
| Volume | 33 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - 6 Sept 2018 |
| Externally published | Yes |
Funding
This work was supported by the University Research Facility in Chemical and Environmental Analysis (UCEA), The Hong Kong Polytechnic University. Runsheng Yin was funded by the Chinese Academy of Sciences through the Hundred Talent Plan. The rock reference materials were generously provided by Prof. Yuan Honglin (Northwest University, Xi'an, China). This work was nancially supported by the Research Grants Council (PolyU 152095/14E), and the National Natural Science Foundation of China (No. 41602047 and 91543205).