High Precision Determination of Mercury Isotope Ratios Using Online Mercury Vapor Generation System Coupled with Multi-collector Inductively Coupled Plasma-Mass Spectrometry

A method was developed for high precision measurement of Hg isotope ratios by multiple collector inductively coupled plasma mass spectrometry( MC-ICP-MS) using an on-line Hg reduction technique. The procedure was evaluated to get high precision measurements that were good enough to significantly detect the anticipated small differences in Hg isotope compositions in natural samples. Typically, internal precision was better than 0.02 parts per thousand ( 1 Relative standard error, RSE) on all Hg ratios investigated. The external reproducibility for standard N IST SRM3133 and UM-Almaden secondary solution, nature samples were 0.06 parts per thousand (2SD) and 0.10 parts per thousand (2SD) over the course of 7 months, respectively. The extent of fractionation has been investigated in a series of natural samples from different locations in China. The ratio Hg-202/198 expressed as 5 values (per mil deviations relative to NIST SRM 3133 Hg standard solution) was from -3.48 parts per thousand to 0.633 parts per thousand.