ELECTROANALYTICAL DETERMINATION OF THE HERBICIDE ATRAZINE IN NATURAL-WATERS

Differential pulse voltammetry at the static mercury drop electrode wa s used to establish an electroanalytical procedure for atrazine determ inations in pure and natural waters. The cathodic peaks observed are a ttributed to the reduction of mono and di-protonated species and showe d 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 o f 2 mV/s and 11 mu g/L at 10 mV/s. In natural waters the calculated de tection 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 s olution, respectively. The higher scan rate used for natural waters an alysis allow to improve the detection limit by avoiding the competitio n of contaminants with the processes occurring at the mercury surface. Hydroxyatrazine, the main chemical and photo-degradation product of a trazine does not interfere in the determination method. The main advan tage of this technique is to allow sample analysis without pre-treatme nts or extraction with solvents. The procedure is adequate for further applications in the study of movement, adsorption and degradation of atrazine in soils.