Determination of selected gadolinium-based contrast agents in soil: method validation and application

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Environmental Science

Background:

• Reclaimed water use in agriculture risks soil contamination with persistent compounds like gadolinium-based contrast agents (GBCAs).
• GBCAs are poorly removed by wastewater treatment, leading to environmental release and potential accumulation in soils and crops.
• There is a need for reliable analytical methods to quantify GBCAs in soil matrices.

Purpose of the Study:

• To develop and validate a robust analytical method for determining GBCAs (gadoteric acid, gadoteridol, gadobutrol) in clay soil.
• To assess the environmental accumulation of GBCAs in soils irrigated with reclaimed water.
• To provide a tool for monitoring the environmental fate and potential food chain transfer of GBCAs.

Main Methods:

• Development and validation of an ion chromatography coupled to inductively coupled plasma mass spectrometry (IC-ICP-MS) method.
• Optimization of mobile phase and elution conditions for efficient GBCAs separation within 7.5 minutes.
• Evaluation of extraction protocols: mild ammonium nitrate for bioavailable fraction and alkaline potassium hydroxide for quantitative recovery.

Main Results:

• The validated IC-ICP-MS method achieved low limits of detection (LOD < 2 ng g⁻¹) and quantification (LOQ < 5 ng g⁻¹).
• The study successfully quantified GBCAs in clay soil from agricultural fields and municipal parks irrigated with reclaimed water for the first time.
• Alkaline extraction demonstrated high recovery (80%) for gadoteric acid in peat substrates, confirming GBCAs accumulation in irrigated cultivation trials.

Conclusions:

• A reliable and sensitive method for GBCAs determination in soil was established, enabling accurate environmental monitoring.
• The findings confirm the accumulation of GBCAs in soils and peat substrates irrigated with reclaimed or fortified water.
• Robust analytical workflows are essential for assessing GBCAs' environmental impact and their potential transfer into the food chain.