Triazine herbicides have been extensively applied to pre ? and post ? emergence weed control. Many studies were focused to ecological and health hazards of these compounds and their toxic effects are very well known. For this reason, the use of some triazine pesticides has been banned in some countries or their permitted levels in drinking water is very low (10-1 mg / L), so that analytical procedures for quantitative determination of several triazines, as well as their degradation products, at low levels are greatly requested [1].
In this communication the transfer mechanism of three s- triazine herbicides, atrazine (ATR), propazine (PRO) and prometrine (PROM), across the water / 1,2 ? dichloroethane interface is investigated using cyclic voltammetry as a previous study to the quantitative determination of these herbicides in water. The analysis was carried out considering the variation of the positive peak potential and the peak current with pH, according to reference [2].
A facilitated proton transfer mechanism from the aqueous to organic phase is demonstrated for ATR and PRO. A different behavior is observed for PROM at low pH values. In this case the direct transfer of protonated PROM occurs. These differences can be explained taking into account the partition coefficients and the dissociation constants of the three protonated species.
It is shown that the determination of the herbicides in aqueous solutions in the concentration range 2.5 x 10-5 M ? 5 x 10-4 M is possible under the experimental conditions employed.
