Molecularly Imprinted Polymers: Providing Selectivity to Sample Preparation
In spite of the huge development in analytical instrumentation, sample preparation is still considered the bottle-neck of the whole analytical process. Nowadays, several sample preparation techniques are available for the extraction and clean-up of target analytes from any kind of sample. However, these techniques suffer from a lack of selectivity, making the final determination of target analytes at the low concentration levels nowadays required difficult in most cases. In this regard, molecularly imprinted polymers (MIPs), synthetic tailor-made materials, are able to selectively bind a target molecule in preference to other closely related compounds, thus making them ideal materials to perform selective extractions. The incorporation of MIPs as sorbents in solid-phase extraction, so-called “molecularly imprinted solid-phase extraction” (MISPE), is already accepted in analytical laboratories and some MIPs (both in bulk and/or packed in cartridges) are commercially available. Besides, MIP incorporation to other sample preparation techniques, such as solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE) or matrix solid-phase dispersion (MSPD), has been recently proposed and successfully applied to the extraction of different analytes from complex samples. Finally, the recent combination of MIPs with liquid membranes circumvents the traditional lack of recognition associated to MIPs in aqueous media thus opening new areas of application.