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A recently developed monoclonal antibody-based ELISA kit for neonicotinoid insecticide imidacloprid was evaluated for its reproducibility, accuracy, and comparability to results from a conventional high-performance liquid chromatography (HPLC) technique for the determination of residual imidacloprid in agricultural products (cucumber, eggplant, lettuce, and green pepper). A method in which imidacloprid is extracted from each agricultural sample as simple, rapid, and efficient as possible was examined for application to screening field analysis, finally. When each extract was diluted 10-fold and over with water prior to ELISA determination, no significant matrix interference was observed besides spinach. The recovery values from fortified samples and reproducibility were very good (average recovery values ≥85.3%; CV values ≤24.0%). The correlation between methods was excellent ( r ≥0.91). The ELISA kit is a suitable screening method for quantitative and reliable determination of imidacloprid in vegetables even without sample clean-up, which saves time and money and considerably increases sample throughput.

A l -leucine-seed-modified quartz crystal microbalance (QCM) oscillator showed selectively chiral discrimination in situ for leucine enantiomers. The obtained results exhibited strong QCM response to l -leucine, but the response to d -leucine was negligible. This selectivity was attributed to preferential crystallization of l -leucine at the solid-solution interface.

A self-assembly monolayer (SAM) of phosphorylated 11-mercapto-1-undecanol (MUD) on a quartz-crystal microbalance (QCM) gold electrode was served as an interfacial layer for subsequent adhesion of barium sulfate crystals. The subsequent process of anchoring barium sulfate crystals on the phosphorylated MUD organic film was followed using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The atomic concentration measured by XPS supported the growth of barium sulfate crystal on the phosphorylated MUD SAM on the QCM gold electrode surface. The AFM image of the barium sulfate crystals grown on the phosphorylated MUD SAM showed a smaller surface roughness than those of the MUD and of the phosphorylated MUD SAM. The observed QCM frequency change per unit time of the modified QCM oscillator was found to be proportional to the square of the relative supersaturation of barium sulfate. This also indicated the crystal growth of barium sulfate at the solid/solution interface. The response (−Δ F ) of the modified QCM oscillator increased with increasing sulfate ion concentrations in adjacent sample solutions ranging 6.8×10 −5 –4.5×10 −3 M at pH 7.2. These responses were due to the selective adsorption of sulfate ions on the barium sulfate crystals at the solid/solution interface. The relative standard deviation was found to be less than 3%. The order of relative anion selectivities for the QCM frequency change of the modified QCM oscillator was: sulfate ion>carbonate ion≫NO − 3 , I − , Br − , SCN − . These relative selectivities were attributed to the differences in solubility product and solubilities for the salts of each anion with barium(II) ion.