Speciation of gadolinium based MRI contrast agents in environmental water samples using hydrophilic interaction chromatography hyphenated with inductively coupled plasma mass spectrometry

Abstract

A highly sensitive method for the determination of gadolinium based MRI contrast agents in environmental water samples has been developed using hydrophilic interaction chromatography (HILIC) coupled with inductively coupled plasma mass spectrometry (ICP-MS). The contrast agents used in the present study are Gd-DTPA (Magnevist), Gd-DTPA-BMA (Omniscan), Gd-DOTA (Dotarem), Gd-BOPTA (Multihance) and Gd-BT-DO3A (Gadovist) which represent both classes of linear and macro cyclic and also ionic and non ionic contrast agents. A study of various parameters responsible for the efficient separation was performed and resulted in an optimum mobile phase composition of 20 mmol L⁻¹ ammonium acetate in 60/40 ACN/water mixture at a flow rate of 0.1 mL min⁻¹ in combination with a micro concentric type PFA nebuliser and ICP-MS detection of the ¹⁵⁸Gd isotope. All contrast agents have shown excellent linearity between 0.1 μg L⁻¹ and 100 μg L⁻¹ (R² > 0.99) for each MRI contrast agent with RSD values found to be less than 2% for triplicate measurements. The limit of quantification (LOQ) for all contrast agents were found to be less than 100 ng L⁻¹ which allows the developed method to be employed in environmental trace analysis. Enrichment of water samples for the determination of contrast agents was performed by using a surface evaporation approach. The developed method has been applied successfully for the separation and determination of contrast agents in surface and waste water treatment plant samples. The MRI agent speciation results were compared with ICP-MS measurements for the total Gd concentrations.