PESTICIDE-RESIDUE ANALYSIS IN FOODS BY NMR .3. COMPARISON OF F-19 NMRAND GC-ECD FOR ANALYZING TRIFLURALIN RESIDUES IN FIELD-GROWN CARROTS

Carrots were grown in trifluralin-treated soil and sampled over a 6-we ek period beginning 6 weeks after seeding. The residue of pesticide an d principal metabolite in the carrot was measured by both F-19 NMR and GC-ECD. The trifluralin concentration was observed to decline from 0. 3 to 0.03 mg/kg. Although there was excellent agreement between the tw o methods at all levels for the parent compound, in general, only the GC method was sensitive enough to measure the low concentrations of th e metabolite.