FLOW-INJECTION POTENTIOMETRIC DETERMINATION OF ATRAZINE IN HERBICIDE FORMULATIONS

A novel atrazinium selective membrane sensor consisting of an atrazine phosphomolybdate ion-pair complex dispersed in a PVC matrix plasticiz ed with dioctylphthalate is described and electrochemically evaluated under static and hydrodynamic modes of operation. The sensor is incorp orated in a flow-through sandwich cell and used as a detector for now injection determination of atrazine herbicide. The intrinsic character istics of the detector in a low dispersion manifold is determined and compared with those of a conventional-shaped sensor. In a phosphate bu ffer of pH 5, the detector exhibits a rapid near-Nernstian response (5 2.3 mV / decade) for atrazinium cation over the concentration range 10 (-2)-10(-5) M. Concentrations as low as 0.3 mu g/ml of atrazine can be detected with an average recovery of 98.3% (mean standard deviation 0 .6%), and the sample input rate is 60 sample per hour. The sensor is u sed for determining atrazine in herbicide formulations, and in extract s of water and soil. No interferences are caused by herbicide diluents and excipients nor by most common anions and cations normally present in water and soil. The results compare favorably with data obtained b y gas liquid chromatography.