Electroanalytical determination of the herbicide atrazine in natural waters

Differential pulse voltammetry at the static mercury drop electrode was used to establish an electroanalytical procedure for atrazine determinations in pure and natural waters. The cathodic peaks observed are attributed to the reduction of mono and di-protonated species and showed to be pH-dependent, with the maximum peak current values at pH 2.3. In pure water, the detection limit found was 5 mu g/L at a scan rate of 2 mV/s and 11 mu g/L at 10 mV/s. In natural waters the calculated detection limits at 10 mV/s were 13 mu g/L and 16 mu g/L for a clean dam and polluted creek waters and 38 mu g/L for a typical tropical soil solution, respectively. The higher scan rate used for natural waters analysis allow to improve the detection limit by avoiding the competition of contaminants with the processes occurring at the mercury surface. Hydroxyatrazine, the main chemical and photo-degradation product of atrazine does not interfere in the determination method. The main advantage of this technique is to allow sample analysis without pre-treatments or extraction with solvents. The procedure is adequate for further applications in the study of movement, adsorption and degradation of atrazine in soils.