Desorption kinetics of antipsychotic drugs from sandy sediments by diffusive gradients in thin-films technique

Dynamic processes of organic contaminants in sediments can have important toxicological implications in aquatic sys-tems. The current study used diffusive gradients in thin-films (DGT) devices in sandy sediments spiked with nine an-tipsychotics and in field sandy sediments. Samplers were deployed for 1 to 30 days to determine the flux of these compounds to DGT devices and the exchange rates between the porewater and sediment solid phase. The results showed a continuous removal of antipsychotics to a binding gel and induced a mobile flux from the DGT device to the adjacent sediment solution. A dynamic model, DGT-induced fluxes in soils and sediments, was used to derive rate constants of resupply of antipsychotics from solid phase to aqueous phase (response time, T-c) and distribution co-efficients for labile antipsychotics. The largest labile pool was found for lamotrigine and carbamazepine in spiked sediments. Carbamazepine, clozapine, citalopram, and lamotrigine were resupplied rapidly by sediments with T-c (25-30 min). T-c values of bupropion and amitriptyline were the longest ( expressionpproximexpressiontely equexpressionl to 5 h), which exhibited slow desorption rates in sediments. In field sediments, high resupply was found for carbamazepine and lamotrigine, which did not show higher labile pool. The T-c values were obviously higher in the filed sediments (52-171 h). Although the adsorption process is dominant for most studied antipsychotics in both spiked sediments and field sediments, the kinetic resupply of an-tipsychotic compounds may not be accurately estimated by laboratory-controlled incubation experiments. More studies are needed to explore the mechanisms of desorption kinetics by using in situ DGT technique in the field.

Automated summary

Dynamic processes of organic contaminants in sediments have toxicological implications in aquatic systems. The study used DGT devices to measure the flux and exchange rates of antipsychotic compounds in sandy sediments. The results showed the continuous removal of these compounds from the sediments and their movement to the adjacent sediment solution. A dynamic model was used to determine the rate constants and distribution coefficients of the antipsychotics. The study highlights the importance of understanding the desorption kinetics of contaminants in sediments.