Hg isotopic composition and total Hg mass fraction in NIES Certified Reference Material No. 28 Urban Aerosols

Abstract

An interlaboratory study on the National Institute for Environmental Studies (NIES) certified reference material (CRM) No. 28 Urban Aerosols, collected on the filters of a central ventilating system in a building in Beijing city center, was performed to obtain informative values of Hg isotopic composition and total Hg (THg) mass fraction. The THg mass fraction was determined by four organizations using atomic absorption spectrometry; it resulted in the mean value of 1.19 ± 0.12 mg/kg (2SD, n = 24). The Hg isotopic composition of the CRM was measured and intercompared at two different institutions by cold vapor generation system coupled to multicollector inductively coupled plasma mass spectrometry. Subsequently, a conventional dissolution method that uses a mixture of HNO₃/HCl/H₂O₂ in Hotblock® and two different dissolution methods that use a mixture of HNO₃/HCl with a microwave and a digestion bomb were applied. The Hg isotopic compositions were δ²⁰²Hg = − 1.26 ± 0.17‰, Δ¹⁹⁹Hg = − 0.23 ± 0.06‰, Δ²⁰⁰Hg = 0.01 ± 0.07‰, and Δ²⁰¹Hg = − 0.22 ± 0.09‰ (2SD, n = 18) for the conventional method, which agree well with those obtained using microwave and bomb digestion. Our results indicate that, for the quality control of particulate matter analyses, this CRM is appropriate for use in environmental and geochemical studies.