Determination of rare earth elements in river water by fully automated on-line column inductively coupled plasma mass spectrometry using iminodiacetate chelate resin as a column

In order to determine ultra-trace levels of rare earth elements (REEs) in river water, fully automated on-line column inductively coupled plasma mass spectrometry (ICP-MS) using iminodiacetate chelate resin as a column was developed in this study. The determination of REEs in a river-water reference material (SLRS-3) was conducted by using the developed method. The obtained results were in good agreement with the recommended values. This developed method was applied to the determination of REEs in Kanda River, which flows through the center of Tokyo, and the distribution patterns of REEs were evaluated. As a result, the positive anormalies of Gd in REEs patterns were found for both river water filtered with a 0.45 mum membrane filter and that filtered and heated with nitric acid. It is considered that the positive anormaly of Gd can be attributed to the outflow of Gd compounds, which are used for MRI (magnetic resonance imaging) contrast medium.