Sorbent selection. To be applied in the acute toxicity test, the passive dosing format should satisfy several prior requirements (i.e., inert, biocompatible, high sorption capacity for the test chemicals). As shown in Figure , the partitioning of C12-BAC from water to XAD2 resin, cation exchange membranes (FKS, FKE), C18 fiber, and all polymer meshes exhibited low log Ksorbent/water (<3). Empore disks (SDB-RPS, C18) and HPTLC sorbed C12-BAC relatively well, but the small particles detached from these materials and suspended in the aqueous phase during the experiment, which would lead to undefined exposure conditions.