ABSTRACT
Solid-phase extraction (SPE) sorbents have undoubtedly simplified tedious sample preparation processes common to drug analyses. This chapter focuses on descriptions, techniques, and benefits of the SPE disks in analytical toxicology. It highlights investigators' experiences with the various disks in the development of drug assays. Second-generation SPE devices in the form of highly efficient disks have improved upon the limited performance of conventional packed-bed SPE columns and liquid/liquid techniques. Most conventional solid-phase sorbents used for drug extractions are chemically modified forms of silica. The heterogeneous surface of the bonded silicas contributes to mixed-mode interactions often observed with analytes on the sorbents. The SPE concentrator unit has a glass fiber prefilter, and the Empore prefilter contains multilayers of polypropylene sheets of graded pore size. The optimal flow rate of liquids through the disks will differ, depending on particle and pore size of sorbent and its packed density in the disk.
