Simultaneous determination of paraquat and diquat in urine by capillary electrophoresis.

Abstract

Qualitative and quantitative detection of paraquat and diquat in urine was performed by capillary zone electrophoresis (CZE). In non-extracted urine, these two closely related herbicides were hydrodynamically or electrokinetically injected into the capillary and well separated in a acidic (pH 3.0) buffer (10 mM glycin, 50 mM NaCl and 20% methanol) within 8 min. The analytes can be identified by their respective migration time with no interfering endogeous compounds around. The peaks were further confirmed by their respective multi-wavelength scanning spectra. Limits of detection (LOD) were 0.2 and 0.1 mg/ml for PQ and DQ, respectively, in nonextracted urine using hydrodynamic injection. Detection sensitivity was greatly improved by solid phase extraction of the compounds followed by CZE using electro-injection under which LODs were 15 and 8 ng/ml for paraquat and diquat respectively. We conclude CZE is a useful method for laboratory diagnosis of herbicide intoxication.