| Abstract
| - The simplicity and flexibility of solid-phase microextraction have been combined with the selectivity of molecularly imprinted polymers (MIPs). Silica fibers were coatedreproducible with a 75-μm layer of methacrylate polymereither nonimprinted or imprinted with clenbuterol tocompare their extraction characteristics under variousconditions. Although the template molecule could beremoved effectively from the imprinted polymer, structural analogues of clenbuterol were used for evaluation.The influence of pH on the extractability of brombuterolwas investigated. Extraction yields up to ∼80% wereobtained when both types of fibers were used to extractbrombuterol from phosphate buffer (pH 7.0). In contrast,yields of about 75 and <5% were obtained when extraction was performed from acetonitrile with imprinted andnonimprinted polymers, respectively, which demonstratesthe selectivity of the MIP-coated fiber. Time sorptionprofiles were measured for the extraction of brombuterolfrom buffer and acetonitrile at the 10 and 100 ng/mL levelwith both types of fibers in order to compare extractioncharacteristics. Equilibrium times of about 30 and 90 minwere found for the extraction of brombuterol from acetonitrile and buffer, respectively. The MIP-coated fiberswere capable of extracting five structural analogues ofclenbuterol from both buffer and acetonitrile, whichsuggests that the amine alcohol part of these moleculesis responsible for interaction with the imprinted polymer.To achieve selective extraction of brombuterol from human urine, MIP-coated fibers were washed with acetonitrile after the extraction. Clean extracts and yields of ∼45%were obtained, demonstrating the suitability of MIP-coated fibers for the analysis of biological samples.
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