Determination of the Mercury Isotopic Ratio by Cold Vapor Generation Sector Field–Inductively Coupled Plasma–Mass Spectrometry Using Lead as the Internal Standard

ABSTRACT

Lead was applied as an internal standard for the determination of Hg isotopic ratios. Cold vapor generation (CV) coupled with sector field–inductively coupled plasma–mass spectrometry (CV-SF-ICP-MS) was used for determination of Hg. It was effective to avoid interferences of Pb from samples while improving the sensitivity of Hg isotopic analysis by an approximate factor of 45 times higher than the aerosol mode. CV-SF-ICP-MS system was constructed and operational parameters were optimized. Research showed that the long stability of the system was limited by SF-ICP-MS and had no relationship with CV under the optimized conditions. The optimized precision of Hg isotopic ratio analysis was approximately 0.1% during 4 h. Five models were applied for the mass bias correction and the Baxter model obtained the smallest relative difference, 0.52‰. The results showed that the mean value of NIST SRM 3133 Hg isotopic ratios obtained by Pb internal standard was nearly identical with the value for Tl. The same performance was also obtained in two environmental reference materials. The results show that Pb may be used as the internal standard for determination of Hg isotopic ratio instead of Tl.

KEYWORDS:

• Cold vapor generation
• inductively coupled plasma–mass spectrometry (ICP-MS)
• isotopic ratios
• lead
• mercury

Acknowledgments

The authors also sincerely thank Prof. Dr. Guangli Xiu from East China University of Science and Technology for providing the Hg isotope standards.

Additional information

Funding

This work was supported by the Strategic Pilot Project of the Chinese Academy of Sciences (XDA 02002400) and Development and Application of Gelatin Preparation Process (2.0) by Green Enzymic Method (KFJ-STS-ZDTP-016).