Adsorption and Transformation of Ivermectin with Soil Minerals.

Ivermectin is a macrocyclic lactone belonging to the avermectin family of compounds and is used as an antiparasitic agent in humans and animals.  The application of ivermectin in intensively reared animal systems has resulted in concerns about potential environmental effects due to its high toxicity to invertebrates.  Ivermectin is mainly excreted in the feces and urine in all animal species regardless of the route of administration, and account for more than 90% of the administered dose.  An increased understanding of sorption processes of ivermectin in soils are needed to refine the environmental risk assessment.  Experiments are ongoing to examine the sorption and transformation of ivermectin with soil and pure mineral phases (i.e., kaolinite, goethite, gibbsite, birnessite).  Iron and manganese oxides (i.e., goethite, birnessite) are of particular interest due to their highly reactive surfaces that can induce the abiotic transformation of organic pollutants.   In this study, sorption and transformation products of ivermectin upon reaction with soil minerals are being determined via ion trap LC-MS/MS analysis.