The application of molecular imprinting technology to solid phase extraction

In parallel to a long lasting search for universal multi-purpose sorbents, the area of solid phase extraction (SPE) is recently experiencing a rapid d evelopment of new types of tailor-made class specific or compound-specific sorbents which are designed to respond to the increasing demand for selecti vity and efficiency in sample clean-up prior to quantification. An importan t issue here is the enrichment and clean-up of complex samples, such as env ironmental waters, sediments, biofluids and foodstuffs prior to detection. This because the analyte is often present in low concentration in a complex mixture of similar compounds and therefore needs to be isolated and enrich ed in order to be detected by standard analytical techniques. The fact that molecularly imprinted polymers (MIPs) can in principle be pre pared against any low molecular weight target molecule, can endure harsh wo rking conditions and work in organic solvents makes them extremely attracti ve as class or compound-specific sorbents. This review critically discusses the application of the technology of molec ular imprinting to solid phase extraction with examples of the different ap proaches (off-line, on-line, coupled column), the different sorbent formats (cartridge, membrane, solid phase microextraction (SPME)) and the differen t protocols (selective adsorption, selective desorption) taken from the lit erature. The issues involved in the development of a new MISPE protocol (choice of t emplate functional monomer, crosslinker, evaluation of the phase and valida tion of the extraction protocol) and the problems associated with the bleed ing of non-extracted template are also discussed.