Molecularly imprinted polymers (MIPs) are prepared using a templated polymerisation and possess selectivity towards a predetermined target (the template). Even though MIPs have been used as stationary phases in chromatography during several decades their use in isocratic mode is still hampered by the severe peak broadening, and thus low efficiency, that is caused by the heterogeneity of the binding sites in the MIP. One approach that was believed to improve the chromatographic efficiency of the MIP columns was miniaturisation and adaptation to the capillary format. Capillary electrochromatography (CEC) was identified as a technique that potentially could improve the efficiency of MIP chromatography. Several different MIP formats were developed to fit the capillary format, among which one of the recent is the nanoparticle MIP format. Even though the separation efficiency problems were not completely solved several interesting advantages of the MIP nanoparticle format were discovered. A partial filling application of CEC was developed that among other advantages offered a new selector phase for every new separation, fast and easy alteration in column selectivity as well as easy design of "columns" for demanding and complex separation tasks. Molecularly imprinted polymers (MIPs) are polymers that contain binding sites selective towards a predetermined target that are determined prior to synthesis of the polymer (fig. 1) [1]. There are several advantages of the MIP over other types of affinity materials. One obvious advantage is the stability of the MIP, it can be operated and washed under very harsh conditions. Another is the ease of synthesis, it is very straight forward to synthesise a MIP. However, one disadvantage is that not all molecules can be successfully imprinted. Another disadvantage is that the MIP suffers from binding site heterogeneity and/or mass transfer restrictions that in chromatography results in that the peak corresponding to the imprinted component becomes exceptionally tailing. The peak tailing has considerably limited the use of MIPs in chromatography and a solution to this would be highly warranted. Besides from having been used as stationary phase in chromatography, MIPs have also been used for e.g. binding assays, as solid phase extraction (SPE) sorbent, as catalyst and as recognition element in sensors.
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