Absolute determination method using chirality for glufosinate and bialaphos by γ-cyclodextrin modified capillary zone electrophoresis

A novel absolute determination method using chirality without any calibration curves or comparison standards has been proposed for phosphorus-containing amino acid-type herbicides. glufosinate (D,L-GLUF) and bialaphos (BLAL). This method is based on a change in the enantiomeric ratio after the spiking of a known amount of the enantiomers with different enantiomeric ratios to a sample. D,L-GLUF was determined by adding a known amount of L-GLUT to the sample, derivatizing them with dansyl chloride, and measuring the ratio of the peak area of the D-isomer to that of the L-isomer by means of gamma-cyclodextrin modified capillary zone electrophoresis. The accuracy and precision of the method were evaluated using a synthetic sample. The mean values obtained for D- and L-GLUF agreed with the values taken within 1.6%; also the reproducibility was as good as less than 2.8%. The determination of BLAL was achieved by determining GLUF quantitatively produced by the acid hydrolysis of BLAL. The proposed methods were applied to the analysis of commercial herbicides and the validity and usefulness were evaluated.