Study of Speciation Analysis Methods for Gd Contrast Agents by LC-ICP-MS Using an Ion Exchange Column

Abstract

Recently, there has been a concern about specific increases in Gd concentrations in environmental waters compared with other rare earth elements. Hydrophilic interaction liquid chromatography coupled with ICP-MS is used for speciation analysis of Gd contrast agents. Here, we aimed to detect these agents by general specification ICP-MS for environmental analysis using an ion exchange column with an aqueous solvent. Using GL-science SYPRON AX-1 and a carbonate-bicarbonate buffer, four Gd contrast agents ―Gd-DTPA-BMA, Gd-BT-DO3A, Gd-DTPA, and Gd-EOB-DTPA― were separated by stepwise elution (switching between two different concentration solvents). The method detection limit (MDL) for a river water sample of Gd contrast agents is similar to that previously reported (Gd-DTPA-BMA: 2.7 ng of Gd/L, Gd-BT-DO3A: 4.4 ng of Gd/L, Gd-DTPA: 1.3 ng of Gd/L and Gd-EOB-DTPA: 3.3 ng of Gd/L), and applicable to environmental river water samples. On the other hand, some issues were observed in the MDL for sea water samples due to the influence of coexisting salts.