Selective Sorbent For Solid-phase Extraction Research Articles

Molecularly imprinted polymers: new molecular recognition materials for selective solid-phase extraction of organic compounds.

During the last few years molecularly imprinted polymers have appeared as new selective sorbents for solid-phase extraction of organic compounds in different samples. Molecular imprinting technology involves the preparation of a polymer with specific recognition sites for certain molecules. Once the polymer has been obtained, it can be used in solid-phase extraction protocols, where a careful selection of the most appropriate solvents to be used in the different steps (sample loading, washing and elution) is needed in order to extract the target analyte selectively. This review describes the state of the art of this methodology, including the preparation of imprinted polymers, a process description for molecularly imprinted solid-phase extraction, as well as more recent applications. It is concluded that molecularly imprinted solid-phase extraction is a powerful tool to selectively isolate certain analytes, and future advances are to be expected in order to widen the field of application.

A highly selective solid phase extraction sorbent for pre-concentration of sameridine made by molecular imprinting

A novel approach to solid phase extraction, based on the use of a highly selective molecularly imprinted polymer, is presented. The versatility of this type of sorbent for solid phase extraction was demonstrated in a model batch-wise pre-concentration of sameridine prior to gas chromatography. Problems associated with leakage of remaining imprint molecules during the desorption phase could be eliminated by the use of a close structural analogue of sameridine as the imprint species. It was found that a major benefit of the imprinted polymer was its specificity, which lead to distinctly cleaner chromatographic traces and ability to improve sensitivity by extracting sameridine from larger sample volumes.

Determination of N-methylcarbamate pesticides in environmental water samples using automated on-line trace enrichment with exchangeable cartridges and high-performance liquid chromatography

A fully automated high-performance liquid chromatographic (HPLC) method was developed for the determination of N-methylcarbamate pesticides and their polar metabolites in various types of water. Two different, commercially available, automated trace enrichment devices (OSP-2 and Prospekt) were investigated as to their performance. Low-carbon C 18-bonded silica (C 18/OH, 40 μm particle size) was used, as a selective sorbent for solid-phase extraction and preconcentration of N-methylcarbamate pesticides from environmental water samples. PLRP-S (15-25 gmm), a styrene-divinylbenzene polymeric phase, was also evaluated as an alternative to extract N-methylcarbamates. After preconcentrating the N-methylcarbamates on an exchangeable cartridge, the analytes were eluted with the mobile phase gradient and transferred to the reversed-phase HPLC system. Detection was performed via post-column hydrolysis on a solid-phase catalyst (anion exchanger), derivatization of the methylamine formed with o-phthalaldehyde reagent, and fluorescence detection of the isoindole derivative. Both trace enrichment systems showed good quantitative results for the determination of N-methylcarbamates and their metabolites at the 0.1 μg/1 level. The repeatability was excellent with relative standard deviations in the range 2–10%. The method detection limits for surface water were between 30 and 50 ng/1. Sample throughput is about 30 samples per 24 h, unattended. The method proved to be suitable for monitoring N-methylcarbamate pesticides in environmental water samples.