VOLTAMMETRIC BEHAVIOR OF SOME NITROPESTICIDES AT THE MERCURY DROP ELECTRODE

Classical DC-polarography and fast scan differential pulse voltammetry (FSDPV) were applied to study the reduction mechanism of five nitrope sticides (trifluralin, benfluralin, pendimethalin, bromofenoxim, fluor oglycofen-ethyl) at a dropping mercury electrode (DME) and at a static mercury drop electrode (SMDE) in a medium of 47-49% (v/v) alcohol or 10-20% (v/v) dimethylformamide. The nitro groups were reduced to hydro xylamine derivatives or further to the corresponding amines depending on the type of compound and of solution acidity. The determination of nitropesticides was performed using FSDPV and adsorptive stripping vol tammetry (AdSV) in model samples. The relative standard deviations wer e smaller than 4.5% for concentrations higher than 2 ng/ml. The detect ion limits were found both experimentally and calculated from regressi on analyses. According to the experimental conditions their values wer e in the range 17-160 ng/ml or 0.1-2.8 ng/ml for FSDPV or AdSV, respec tively. The nitropesticides in artificially contaminated soils were de termined after two to three times extraction with acetone. The recover y was about 96%.