Magnetic molecularly imprinted polymer nanoparticles for the extraction and clean-up of thiamethoxam and thiacloprid in light and dark honey.

In this work, new selective and sensitive dual-template molecularly imprinted polymer nanoparticles (MIPs) were synthesized and characterized. Sorbent MIPs were investigated for simultaneous extraction and clean-up of thiamethoxam and thiacloprid from light and dark honey samples. In this study, ultra-high-performance liquid chromatography-tandem mass spectrometry triple-quadrupole (UHPLC-MS/MS) (QQQ) was used to detect and quantify the pesticides. The kinetic model with adsorption kinetics of sorbent was investigated. The optimal adsorption conditions were 80 mg of polymer MIPs, a 30-min extraction time, and a pH of 7. The detection limit (LOD) and the quantification limit (LOQ) varied from 0.045 to 0.070 µg kg-1 and from 0.07 to 0.10 µg kg-1, respectively. The intra-day and inter-day precision (RSD, %) ranged from 1.3 to 2.0% and from 8.2 to 12.0%, respectively. The recovery of thiamethoxam and thiacloprid ranged from 96.8 to 106.5% and 95.3 to 104.4%, respectively, in light and dark honey samples.

Spectroscopic studies for the inclusion complexation of ketoprofen enantiomers with ß-cyclodextrin.

Inclusion complexes of R-ketoprofen and S-ketoprofen enantiomers with ß-cyclodextrin (ß-CD) in aqueous solution were studied using various spectroscopic techniques such as Raman, FTIR, UV and fluorescence. The different relative intensities and characteristic band shifts of the two enantiomers from Raman spectra suggests different interaction when complexed with ß-CD. Raman experiments revealed a noticeable diminishing of the CC vibration and ring deformation, which indicate the embedding of ketoprofen inside the ß-CD cavity. It's revealed that distinct differences between R- and S-ketoprofen in the presence of ß-CD at neutral pH. The stoichiometry ratio and binding constant of the inclusion complexes were calculated using Benesi-Hildebrand plot. Both enantiomers showed stoichiometry ratio of 1:1 inclusion complex with ß-CD. The binding constant of R-ketoprofen (4088 M-1) is higher than S-ketoprofen (2547 M-1). These values indicated that ß-CD formed inclusion complexes more preferentially with R-ketoprofen than S-ketoprofen. Results demonstrated that ß-CD can be used as a promising chiral selector for ketoprofen enantiomers.