Sensitive determination of paraquat and diquat at the sub-ng ml-1 level by continuous amperometric flow methods.
Two methodologies are described for the determination of paraquat and diquat. The first is based on the pre-treatment of an electrode with a surfactant solution, which improves the electrochemical determination of the herbicides. Linear calibration graphs were obtained in the ranges 10-80 and 10-100 ng ml-1 for paraquat and diquat, respectively. The limits of detection were 6.32 for paraquat and 4.80 ng ml-1 for diquat. The method was applied to the determination of the herbicides in synthetic water samples. The second methodology is based on the preconcentration of paraquat and diquat in a minicolumn packed with a cation-exchange material. The determination ranges and detection limits depend on the sample volume used (5-50 ml). Thus, 50 ml of sample provides limits of detection of 0.016 and 0.020 ng ml-1 for paraquat and diquat, respectively. The applicability of the method was demonstrated with the determination of the herbicides in both synthetic and real water samples.
Luque
M
M
Department of Analytical Chemistry, Faculty of Sciences, University of Córdoba, Spain.
Ríos
A
A
Valcárcel
M
M
D004178:Diquat / Q000032:analysis*; D004563:Electrochemistry; D006540:Herbicides / Q000032:analysis*; D010269:Paraquat / Q000032:analysis*; D014877:Water Pollution, Chemical
D006540:Herbicides; D004178:Diquat; D010269:Paraquat