Gas chromatographic method for determination of uracil herbicides in roots of Echinacea angustifolia Moench (Asteraceae).

A GC/NPD method and a rapid screening TLC method were developed for the simultaneous determination of uracil herbicide residues (bromacil, lenacil, terbacil) in the roots of Echinacea angustifolia Moench (Asteraceae). The uracil herbicide residues were extracted into acetone. After evaporation of acetone from the acetone-water extract the residue was dissolved in water-methanol (5:1 v/v). Cyclohexane was used for removal of the non-polar co-extractives in the sample matrix. After separation of the cyclohexane phase the uracil herbicide residues were extracted into chloroform. This extract was purified on a Florisil column, and residues were eluted with dichloromethane-acetone (9:1, v/v). The cleaned up extract was analysed by the GC/NPD method on a capillary column DB-1 using atrazine as internal standard. A minimum recovery of 70% was attained for contamination levels of 0.02-0.40 mg kg(-1).