Water compatible stir-bar devices imprinted with underivatised glyphosate for selective sample clean-up.

This paper reports the development of stir bars with a new MIP based coating, for the selective sorptive extraction of the herbicide glyphosate (GLYP). Molecular imprinting of the polymer has directly been carried out employing underivatised GLYP as the template molecule. Due to the poor solubility of the target compound in organic solvents, the MIP methodology has been optimised for rebinding in aqueous media, being the synthesis and the rebinding steps carried out in water:methanol mixtures and pure aqueous media. The coating has been developed by radical polymerisation initiated by UV energy, using N-allylthiourea and 2-dimethyl aminoethyl methacrylate as functional monomers and ethylene glycol dimethacrylate as the cross-linker. Mechanical stability of the coating has been improved using 1,3-divinyltetramethyldisiloxane in the polymerisation mixture. Under the optimised conditions, the MIP has demonstrated excellent selectivity for the target compound in the presence of structural analogues, including its major metabolites. The applicability of the proposed method to real matrices has also been assessed using river water and soil samples. Registered mean recoveries ranged from 90.6 to 97.3% and RSD values were below 5% in all cases, what confirmed the suitability of the described methodology for the selective extraction and quantification of GLYP.

Enantioselective extraction of (+)-(S)-citalopram and its main metabolites using a tailor-made stir bar chiral imprinted polymer for their LC-ESI-MS/MS quantitation in urine samples.

This paper reports the application of a chiral imprinted polymer (CIP)-coated stir bar for the selective extraction of (+)-(S)-citalopram (SCIT) and its main metabolites, (+)-(S)-desmethylcitalopram (SDCIT) and (+)-(S)-didesmethylcitalopram (SDDCIT), from urine samples. The developed device has been demonstrated to be capable of selectively extracting the three target analytes from urine samples without saturating the imprinted sites. A CIP-coated stir bar sorptive extraction procedure (CIP-SBSE) is proposed for the isolation of SCIT, SDCIT and SDDCIT followed by their subsequent analysis using liquid chromatography ion trap mass spectrometry (LC-ITMS). Deuterated SCIT-d6 was used as an internal standard. The method was validated using a standard procedure, which revealed that a quantification of 5 ng mL(-1) was obtained in urine samples and that the accuracy and precision were within the established values while no matrix effect was observed.

Rational design and chromatographic evaluation of histamine imprinted polymers optimised for solid-phase extraction of wine samples.

This article reports on the computational design, development and application of a molecularly imprinted polymer (MIP) with specific affinity towards histamine. Computational modelling was used to screen a monomer library in order to select the monomers able to form the strongest complex with the target analyte. These were subsequently used for MIP synthesis by radical polymerisation initiated by UV. MIPs were then evaluated by liquid chromatography and solid phase extraction (SPE) and best MIP behaviour was observed when itaconic acid was used as functional monomer. Finally, after optimisation of the polymer composition, MIPs were used as adsorbents for SPE and clean-up of histamine in wine samples. The proposed histamine extraction method with the MIP-SPE cartridge was found to be reproducible (<5% RSD) and accurate (93-99% recovery) and provided clear wine extracts. The described methodology is simple and fast and is suitable for the selective histamine extraction and its subsequent quantification by HPLC-DAD from complex matrices such as wine samples.