Determination of zearalenone by liquid chromatography/tandem mass spectrometry and application to a pharmacokinetic study

Zearalenone, a mycotoxin biosynthesized by various Fusarium fungi, is widely found as a contaminant in grains and animal feeds. This study describes a rapid and sensitive LC/MS/MS assay method for the quantification of zearalenone in rat serum. The assay was validated to demonstrate the specificity, linearity, recovery, lower limit of quantification (LLOQ), accuracy and precision. The multiple reaction monitoring was based on the transition of m/z 317.0 → 130.9 for zearalenone and 319.0 → 204.8 for zearalanone (internal standard). The assay utilized a single liquid–liquid extraction with t‐butyl methyl ether and isocratic elution, and the LLOQ was 0.5 ng/mL using 0.1 mL rat serum. The assay was linear over a concentration range from 0.5 to 200 ng/mL, with correlation coefficients >0.9996. The mean intra‐ and inter‐day assay accuracy was 101.2–112.9 and 96.3–108.0%, respectively. The mean intra‐ and inter‐day precision was between 1.3–7.6 and 3.6–10.6%, respectively. The developed assay was applied to a pharmacokinetic study after a bolus intravenous injection of zearalenone in rats. Copyright © 2009 John Wiley & Sons, Ltd.     

Heterogeneous asymmetric Henry reaction using a chiral bis(oxazoline)-copper complex immobilized on magnetically separable mesocellular mesoporous silica support

A chiral bis(oxazoline) ligand was immobilized onto a magnetically separable hierarchically-ordered mesocellular mesoporous silica (M-HMMS) and this new catalytic system was examined in the asymmetric Henry reaction between various aldehydes and nitromethane at ambient temperature. Good enantioselectivity (upto 86.0% ee) was observed when the free silanol groups of the mesoporous silica were capped by trimethylsilyl group. This catalyst was separated magnetically and reused several times without significant loss of reactivity or enantioselectivity. This magnetic separation of catalysts could lead to further development toward practical industrial scale application due to simplicity without cumbersome filtration.     

Effect of surface roughness on leakage current and corrosion resistance of oxide layer on AZ91 Mg alloy prepared by plasma electrolytic oxidation

The influence of the surface roughness of Mg alloys on the electrical properties and corrosion resistance of oxide layers obtained by plasma electrolytic oxidation (PEO) were studied. The leakage current in the insulating oxide layer was enhanced by increasing the surface roughness, which is a favorable characteristic for the material when applied to hand-held electronic devices. The variation of corrosion resistance with surface roughness was also investigated. The corrosion resistance was degraded by the increasing surface roughness, which was confirmed with DC polarization and impedance spectroscopy. Pitting corrosion on the passive oxide layer was also analyzed with a salt spray test, which showed that the number of pits was not affected by the surface roughness when the spray time reached 96 h.     

Regio- and stereoselective acylation of saturated carbocycles via Norrish-Yang photocyclization

A regio- and stereoselective acylation of saturated carbocycles has been achieved through two-step reactions involving the Norrish-Yang photocyclization of 1,2-diketones and subsequent ring opening of the α-hydroxy-cyclobutanones. The C-H activation of the carbocycle proceeds regioselectively at vicinal to the diketone moiety resulting in stereoselective formation of cis-fused bicycles. The following C-C cleavage affords vicinally cis-acylated carbocycles. Predictability, generality, and practicality of the present strategy have been demonstrated using variously modified saturated carbocycles.