Validation of an isotope dilution, ICP-MS method based on internal mass bias correction for the determination of trace concentrations of Hg in sediment cores

The development and validation of a method for the determination of mercury in sediments using a sector field inductively coupled plasma mass spectrometer (SF-ICP-MS) for detection is described. The utilization of isotope dilution (ID) calibration is shown to solve analytical problems related to matrix composition. Mass bias is corrected using an internal mass bias correction technique, validated against the traditional standard bracketing method. The overall analytical protocol is validated against NRCC PACS-2 marine sediment CRM. The estimated limit of detection is 12 ng/g. The proposed procedure was applied to the analysis of a real sediment core sampled to a depth of 160 m in Lake Como, where Hg concentrations ranged from 66 to 750 ng/g.