An alternative and fast method for determination of glyphosate and aminomethylphosphonic acid (AMPA) residues in soybean using liquid chromatography coupled with tandem mass spectrometry

A simple and specific method using reversed‐phase liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) was investigated, which allowed the determination of residues of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), in soybean samples. An aqueous extraction with liquid‐liquid partition followed by protein precipitation was performed before the LC/MS/MS determination. The quantitation of glyphosate and AMPA was performed in positive and negative ESI mode, respectively, using the multiple reaction monitoring (MRM) mode with three transitions for each analyte to enhance the specificity of the method and avoid false positives. The methodology reported in this work is capable of detecting residues of glyphosate and AMPA in soybean samples with limits of quantification of 0.30 and 0.34 mg kg^?1, respectively. This alternative method has throughput advantages such as simpler sample preparation and faster chromatographic analysis. Copyright © 2009 John Wiley & Sons, Ltd.     

Chiral bromine–lithium exchange catalyzed by diamines

Different classes of prochiral polyhalide compounds have been tested in a chiral bromine–lithium exchange in the presence of different diamines with enantiomeric excesses of up to 63%.     

Une classe de séries trigonométriques qui convergent presque partout vers zéro

Sans résumé     

First Total Syntheses of Novel Non-Enzymatic Polyunsaturated Fatty Acid Metabolites and Their Identification in Edible Oils

Oxidative stress (OS) is an in vivo process leading to free radical overproduction, which triggers polyunsaturated fatty acid (PUFA) peroxidation resulting in the formation of racemic non-enzymatic oxygenated metabolites. As potential biomarkers of OS, their in vivo quantification is of great interest. However, since a large number of isomeric metabolites is formed in parallel, their quantification remains difficult without primary standards. Three new PUFA-metabolites, namely 18-F_3t-isoprostane (IsoP) from eicosapentaenoic acid (EPA), 20-F_4t-neuroprostane (NeuroP) from docosahexaenoic acid (DHA) and 20-F_3t-NeuroP from docosapentaenoic acid (DPA_n-3) were synthesized by two complementary synthetic strategies. The first one relied on a racemic approach to 18(RS)-18-F_3t-IsoP using an oxidative radical anion cyclization as a key step, whereas the second used an enzymatic deracemization of a bicyclo[3.3.0]octene intermediate obtained from cyclooctadiene to pursue an asymmetric synthesis. The synthesized metabolites were applied in targeted lipidomics to prove lipid peroxidation in edible oils of commercial nutraceuticals.