Analytical Sciences

Abstract − Analytical Sciences, 22(12), 1489 (2006).

Absolute Determination Method for Trace Quantities of Enantiomer of Glufosinate by γ-Cyclodextrin Modified Capillary Zone Electrophoresis Combined with Solid-Phase Extraction and On-capillary Concentration
Takayuki ASAMI and Hisanori IMURA
Department of Environmental Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
A highly sensitive and accurate determination method for trace quantities of enantiomers of glufosinate (D,L-GLUF), a phosphorus-containing amino acid-type herbicide, has been studied. The present method is based on the change in the mole ratio of the enantiomeric isomers after spiking of a known amount of an isomer (L-GLUF). The chiral separation and detection were made by γ-cyclodextrin modified capillary zone electrophoresis (γ-CD-CZE) with fluorescence detection. Solid-phase extraction of D,L-GLUF with titania was investigated as the pre-separation method to eliminate coexisting materials such as inorganic salts and organic compounds in river water. A separated D,L-GLUF was labeled with dansyl chloride and subjected to the on-capillary concentration using large-volume sample stacking (LVSS) before γ-CD-CZE. The detection limit of the present method was as low as 2.0 × 10-9 M. The present method was successfully applied to a model sample containing 2.0 × 10-7 M D,L-GLUF in river water. It was confirmed that trace quantities of D-and L-GLUF in environmental samples can be accurately determined without any calibration curves and comparison standards.