Sorption and biosorption of Gd-based contrast agents in the water environment

Abstract

The study presents the characterization of the sorption of Gd(NO3)(3) and Gd-based contrast agents Dotarem (R) and MultiHance (R) by fresh and dry biomass of green algae Chlorella kessleri, humic acids, active carbon and lake sediment. Analysis of Gd in the algae and sorbents was performed by inductively coupled plasma mass spectrometry method including a sample preparation step optimized for this procedure (limits of detection for fresh algae 0.090, for other sorbents 0.023 mg kg(-1)). The algae Chlorella kessleri was cultivated in a growth medium with addition of Gd compounds (2, 20 and 100 mu g L-1 of Gd) from 12 hours to 33 days. The sorption on other sorbents lasted 0.5-12 h. Compared to a blank experiment, the C. kessleri biomass growth was lower in the presence of Gd compounds. The final bioconcentration factors were found to be 400 (Dotarem (R)), 500 (MultiHance (R)) and 1300 (Gd(NO3)(3)) L kg(-1). Sorption efficiencies ranged from negligible amounts to 90%. They decreased in the order Gd(NO3)(3) > MultiHance (R) > Dotarem (R) and, in case of sorbents, active carbon > dry algae biomass > humic acids > lake sediment > fresh algae biomass.