Fibers coated with molecularly imprinted polymers for solid-phase microextraction

The simplicity and flexibility of solid-phase microextraction have been com bined with the selectivity of molecularly imprinted polymers (MIPs), Silica fibers were coated reproducible with a 75-mum layer of methacrylate polyme r either nonimprinted or imprinted with clenbuterol to compare their extrac tion characteristics under various conditions. Although the template molecu le could be removed effectively from the imprinted polymer, structural anal ogues of clenbuterol were used for evaluation. The influence of pH on the e xtractability of brombuterol was investigated. Extraction yields up to simi lar to 80% were obtained when both types of fibers were used to extract bro mbuterol from phosphate buffer (pH 7.0). In contrast, yields of about 75 an d 15% were obtained when extraction was performed from acetonitrile with im printed and nonimprinted polymers, respectively, which demonstrates the sel ectivity of the MIP-coated fiber. Time sorption profiles were measured for the extraction of brombuterol from buffer and acetonitrile at the 10 and 10 0 ng/mL level with both types of fibers in order to compare extraction char acteristics. Equilibrium times of about 30 and 90 min were found for the ex traction of brombuterol from acetonitrile and buffer, respectively. The MIP -coated fibers were capable of extracting five structural analogues of clen buterol from both buffer and acetonitrile, which suggests that the amine al cohol part of these molecules is responsible for interaction with the impri nted polymer, To achieve selective extraction of brombuterol from human uri ne, MIP-coated fibers were washed with acetonitrile after the extraction. C lean extracts and yields of similar to 45% were obtained, demonstrating the suitability of MIP-coated fibers for the analysis of biological samples.