AUTOMATIC CONTINUOUS-FLOW DETERMINATION OF PARAQUAT AT THE SUBNANOGRAM PER MILLILITER LEVEL

A flow-through spectrophotometric sensor for the determination of paraquat at the nanogram per milillitre level based on integration of preconcentration, reaction and detection in the flow-cell is proposed. The determination range achieved depends on the sample volume used. Thus, 250 ml of sample provides detection and determination limits of 0.11 and 0.44 ng ml-1 paraquat, respectively. The relative standard deviation was +/-7.9% for 1.0 ng ml-1 paraquat. The potential interference of other pesticides was studied, and the method was used to analyse water samples and study the adsorption of paraquat in different types of soils.