Abstract

A double focusing sector field inductively coupled plasma mass spectrometer (ICP-MS) was used to determine Cd in two sediment reference materials (National Institute of Standards and Technology Standard Reference Material 1646a and National Institute for Environmental Studies Certified Reference Material No. 2). The isotope dilution method was used for quantification with ¹¹¹Cd and ¹¹²Cd as the two isotopes. The isobaric interference from ¹¹²Sn to ¹¹²Cd was corrected using four interference correction equations. The software correction equation utilizing the natural abundance ratio of ¹¹²Sn∶¹¹⁷Sn resulted in over-estimation of the ¹¹²Sn intensity due to a non-uniform sensitivity of the sector field ICP-MS. The isobaric interference was more properly corrected when the ¹¹²Sn intensity was estimated using a mass bias corrected ¹¹²Sn∶¹¹⁷Sn ratio. Good agreement was achieved with the certified values in the analysis of the two sediment reference materials using the mass bias corrected ratios.