CHEMICAL CONTROLS ON SORPTION AND TRANSPORT OF CETIRIZINE IN SOILS

Recent surveys have found traces of pharmaceuticals and active ingredients in personal care products in drinking water across the world. One such pollutant is cetirizine, an antihistamine found in popular allergy medicines like Zyrtec. Cetirizine is a complex nonpolar molecule with carboxylic acid and amino functional groups which gives the compound its zwitterionic nature. It is also sparingly soluble in water and, hence, it tends to accumulate in soils, sediments, and very importantly, in tissues of organisms that come in contact with this chemical. The main goal of this study is to analyze how cetirizine is sorbed onto soils as a function of soil chemical composition. A and B- horizon soil samples from three different soil series within the Francis Marion National Forest in South Carolina were used for this study. Soils were equilibrated with varying concentrations of cetirizine for a predetermined time to determine how strongly cetirizine sorbed to these soils. Cetirizine in aqueous solution was analyzed using a high performance liquid chromatograph with UV-Vis detector. The sorption isotherms showed that cetirizine was strongly sorbed to soils that had higher clay content and less strongly to soils that contained higher organic matter content. This behavior is attributed to the zwitterionic nature of the compound that results in a cationic form at equilibrium soil pH. The sorption isotherms fit well to the Freundlich model. In order to understand cetirizine’s fate in natural waters, glass columns will be packed with these soils and the transport of cetirizine will be measured in different solution conditions. We expect that soils with higher clay content will experience larger retardation of cetirizine than soils with higher organic matter.