SIMULTANEOUS DETERMINATION OF DIQUAT AND PARAQUAT RESIDUES IN VARIOUSMATRICES BY CAPILLARY ZONE ELECTROPHORESIS WITH DIODE-ARRAY DETECTION

The separation of diquat and paraquat by CZE has been investigated. Th e addition of acetonitrile (10 %, v/v) to a phosphate buffer (100 mM, pH 4.0) is necessary for effective separation of both herbicides at an optimum applied voltage of around 12 kV; the current and migration ti mes were stable and reproducible under these conditions. The method wa s validated for linearity and reproducibility. The detection level cal culated for diquat and paraquat was 30 and 40 nM, respectively in the injection solution. By use of stacking, these detection levels were im proved by a factor of 120. The method is suitable for the determinatio n of both herbicides in samples such as herbicidal formulations, water , soil, potatoes, urine and serum. Photodiode-array detection permitte d the rapid identification of both compounds.