MULTIRESIDUAL METHOD FOR DETERMINATION OF THE URACIL HERBICIDES IN PLANT-SAMPLES BY GC NPD/

GC method is described for the simultaneous determination of the uraci l herbicide residues in some medicinal plants, spinach and strawberrie s. The uracil herbicide (bromacil, lenacil and terbacil) residues were extracted into acetone or acetone-water (95:5, v/v). After evaporatio n of acetone from acetone-water extract the residues were dissolved in water-methanol (5:I, v/v). Cyclohexane was used for removal of the no n-polar co-extractives in sample matrix. After separation of cyclohexa ne phase the uracil herbicide residues were extracted into dichloromet hane. The extract was purified on a Florisil(R) column, residues were eluted with dichloromethane-acetone (95:5, v/v) and analysed by capill ary GC with selective detector (NPD) using a DB-17 column. A minimum r ecovery of 70% was attained on the contamination levels of 0.02-0.2 mg /kg, the limit of detection was 0.005-0.01 mg/kg (S/N = 3). The lenaci l residue content in dry plant of M. piperita L. and M. officinalis L, from the micro-scale experiment was in the range <0.02 to 0.05 mg/kg. Analysis of actual samples of spinach and strawberries produced by fa rm in Slovakia did not show the presence of the uracil herbicide resid ues (the content was below the 0.01 mg/kg).