TP5 Measurement/ Estimation of Environmentally Relevant Physico-Chemical Properties
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(KWO-1117-817950) Adsorption of five selective serotonin reuptake inhibitors to sediments and soils.

Kwon, Jeong-Wook¹, Armbrust, Kevin¹, ¹ Mississippi State Chemical Laboratory, Mississippi State University, Mississippi State, MS, USA

ABSTRACT- Selective serotonin reuptake inhibitors (SSRIs) are widely used for the treatment of clinical depression in humans. Recent reports on the detection of SSRIs in surface water and sediments have heightened concerns about the presence of these emerging contaminants. Adsorption processes are particularly important because they influence the mobility and transports of chemicals in surface and sub-surface environments. The adsorption of five SSRIs (citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline) to two sediments and three soils were investigated using a batch equilibrium methods similar to those employed in pesticide registration studies. Adsorption isotherms followed the Freundlich equation. Greater than 91% of the applied mass of each SSRI sorbed to soil or sediment, except fluvoxamine at 73%, over a range of concentrations of 0.5-10 mg/L, indicating that all SSRIs should strongly sorb to sediments and soils. The isotherm shapes were classified as L-type for most SSRIs. In general pH was the main factor influencing the adsorption of SSRIs to sediments and soils. No correlation between adsorption characteristics and organic matter, CEC or clay content was found. Values of K_f, K_d, and log K_oc ranged from 39 to 18342, from 60 to 42579, and 3.35 to 6.02, showing a very wide range of values depending upon kinds of drug and soil. In conclusion, SSRIs were found to be quickly and highly adsorbed to sediments and soils in the environments and will quickly dissipate from water phase due to adsorption.

Key words: selective serotonin reuptake inhibitors, adsorption, Freundlich equation, isotherm shapes