ADSORPTIVE STRIPPING VOLTAMMETRY IN DISPERSED MEDIA - APPLICATION TO THE DETERMINATION OF THE HERBICIDE TERBUTRYN

The possibility of applying adsorptive stripping voltammetry (AdSV) in dispersed media has been evaluated. Sensitive methods for the determi nation of the herbicide terbutryn at nanomolar levels by AdSV at the h anging mercury drop electrode in micellar and emulsified media are pro posed. The anionic surfactant sodium pentanesulfonate was chosen as th e most suitable agent for micellar solutions and oil-water emulsions. On the other hand, ethyl acetate was used as the organic solvent to fo rm terbutryn emulsions, a systematic study of the various experimental parameters that affect the stripping response was carried out by diff erential pulse voltammetry. When working in a 0.1 molL(-1) perchloric acid medium with an accumulation potential of -0.60V, terbutryn could be determined over the 6.0 x 10(-9) -4.0 x 10(-7) and 6.0 x 10(-9) -2. 0 x 10(-7) molL(-1) ranges in micellar (50s accumulation time) and emu lsified (70s accumulation time) media, respectively. The limits of det ection were 2.2 x 10(-9) and 1.1 x 10(-9) molL(-1),and the relative st andard deviations (n = 10) were 6.3 and 4.3% in micellar and emulsifie d media, respectively. The effect of other coexisting herbicides on th e terbutryn stripping peak was evaluated. Finally, the developed metho d in emulsified medium was applied to the determination of terbutryn i n spiked tap waters.