Gadolinium-based contrast agents (GBCAs), which are used extensively in magnetic resonance imaging (MRI) are known to accumulate in freshwater bodies. Since wastewater treatment plants are unable to remove said GBCAs, there has been a variety of studies measuring anthropogenic Gd in tap water in developed nations. In this poster we present the assessment of the efficiency of commercially available water filters in removing these Gd contaminations. The most commonly used GBCAs, Gd-HP-DO3A, Gd-BT-DO3A and Gd-DOTA, as well as the linear GBCAs, Gd-DTPA and Gd-BOPTA, were considered. For this purpose, a variety of different commercially available filters was compared and their capacity was discussed. Additionally, the effect of active carbon and ion exchange resins was tested independently. Tap water samples from multiple cities in Germany with an emphasis on North Rhine-Westphalia and Berlin were filtered and quantified. The method consisted of an automated sample preparation platform for automatic sampling, inline dilution and ion exchange chromatography, which was coupled with a triple quadrupole ICP-MS. The tested filters showed a large variety in performance with a rapid decrease in retention over time. The tested anion exchange resin proved an outstanding absorption of GBCAs.

As expected, only macrocyclic GBCAs were detected in tap water samples from across Germany due to legal restrictions for linear GBCAs since 2017. We determined concentrations in the expected range up to 92.8 ng L-1 in the former West Berlin area, which is among the highest ever recorded in drinking water in Germany. Furthermore, higher concentrations of up to 22.8 ng L-1 in the Ruhr area were determined. Using the most efficient filters, we were able to show a significant reduction of GBCAs in tap water samples, in many cases below the level of detection. This opens the door for further discussions regarding the removal of GBCAs from drinking waters and the future of wastewater treatment.