172-10 From Medical Waste to Environmental Risk: Examining Gadolinium Speciation Stability in Water Under Different Preservation Conditions

Session: Urban Geochemistry

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Abstract:

Gadolinium (Gd) has emerged as a trace contaminant in aquatic environments due to the widespread use of gadolinium-based contrast agents (GBCAs) in Magnetic Resonance Imaging (MRI) diagnostics. Following injection of GBCAs to patients to enhance image contrast, they are excreted primarily through urine and enter municipal wastewater systems, where they pass largely unchanged through conventional treatment processes before being discharged into receiving waters. The main environmental concern is their potential to release toxic free Gd³⁺, making accurate determination of Gd speciation essential for monitoring.

This study evaluates how preservation conditions including temperature (room temperature, 4 °C, and freezing), acidification, and filtration affect the behavior of Gd chelates in three water matrices: deionized water, tap water, and river water. Samples were spiked with free Gd³⁺ and four GBCAs (Gadovist, Dotarem, Vueway, and Omniscan), and analyzed at multiple time points. Inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography coupled with ICP-MS (IC-ICP-MS) were used to quantify total Gd and assess speciation. The results revealed clear patterns in GBCA stability across preservation methods and water types.

GBCAs showed the most significant concentration losses within the first week, particularly in river water, highlighting the 24-hour mark as the most reliable time point to capture native speciation before transformation occurs. Among water types, river water exhibited the highest variation in recoveries, likely due to complex matrix interactions, while tap water showed moderate changes and deionized water remained largely stable, indicating minimal interference. These matrix effects were further influenced by the chemical structure of the agents: macrocyclic compounds such as Dotarem and Vueway were notably more stable, whereas the linear agent Omniscan degraded more readily across all conditions. Acidification further impacted recoveries, leading to chelate destabilization; especially in Omniscan, where levels dropped to near-zero making acidic preservation unsuitable for speciation analysis. Filtration helped improve recoveries over time, particularly for Omniscan and Vueway at room temperature and freezing, though it had minimal effect at 4 °C. Despite these differences, temperature alone did not appear to be a major factor influencing GBCA stability across water types.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8258

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