title: Solid-phase extraction in clinical biochemistry.
abstract: In order to measure low concentrations of analytes in plasma and urine, it is often necessary to extract and concentrate them. With solid-phase extraction (SPE), this is achieved by partitioning the analytes between a solid and a liquid or headspace vapour. A wide range of high-quality materials is now available to do this, offering a variety of separation modes for different applications. These include partitioning using reversed-phase, normal-phase, ion-exchange, restricted-access and immunoaffinity sorbents or molecularly imprinted polymers and, increasingly, combinations of these processes. Solid-phase microextraction was introduced to analyse volatile and semi-volatile compounds. The range of sampling formats has expanded from simple packed syringes to cartridges, disks, SPE pipette tips and 96-well plates. These developments have facilitated automated off- and on-line sample processing. The basic principles of SPE and the recent innovations are reviewed here. This is a technological growth area. Some of the developments are finding application in clinical toxicology. However, they could also be of wider value in clinical chemistry--for example, for analyses of volatile and non-volatile metabolites, peptides, radioactive elements and trace metal speciation.
authors.affiliation: Department of Chemical Pathology (NHS), General Hospital, Southampton SO16 6YD, UK. valerie.walker@suht.swest.nhs.uk
authors.forename: Valerie
authors.initials: V
authors.lastname: Walker
authors.forename: Graham A
authors.initials: GA
authors.lastname: Mills
mesh_terms: D000327:Adsorption; D000818:Animals; D001331:Automation; D002623:Chemistry Techniques, Analytical / Q000379:methods* / Q000639:trends; D002624:Chemistry, Clinical / Q000295:instrumentation / Q000379:methods*; D006801:Humans