RESUMEN
Dissipation of residues of benzoylurea insecticides teflubenzuron (TFB) and triflumuron (TFM) under field conditions was evaluated on a pear orchard in Greece. Residues were determined by UV-HPLC analysis, with a detection limit of 0.030 mg/kg for both pesticides. TFB residues in pears were found to persist for 2 weeks and decline thereafter with 48% of the initial deposit remaining 42 days after the last application. TFM residues were found to decline following first-order kinetics and with a half-life of 39(+/-7) days. Residues of both pesticides found in pears collected at harvest maturity were lower than the maximum residue limits (MRLs) set by individual countries. Dissipation of TFB and TFM in cold-stored pears was also evaluated. TFB residues were very persistent for the whole storage period, whereas TFM residues did not dissipate for 6 weeks and then showed a constant decline; 7% of the initial concentration remained at the end of the storage period of 29 weeks.
Asunto(s)
Benzamidas/química , Frutas/química , Insecticidas/química , Residuos de Plaguicidas/química , Cromatografía Líquida de Alta PresiónRESUMEN
Dissipation of benzoylurea insecticide teflubenzuron in grapes exposed to field treatments was evaluated. Vines of a white grape vineyard located in central Greece were sprayed twice, at a 28-day interval, with a commercial formulation of the insecticide at 12 g of active ingredient/100 L. Residues were determined by HPLC diode array detection, after ethyl acetate extraction and cleanup on silica phase cartridges, with a detection limit of 0.005 mg/kg. Under field conditions teflubenzuron residues in grapes were found to be very stable with no significant reduction for the whole experimental period of 49 days. However, residues were slightly lower than the maximum residue limits set by individual countries. The fate of teflubenzuron during the vinification process was also studied. Residues were found to be transferred completely into the must but, due to their high affinity for the suspended matter, were removed by approximately 98%; thus, very low concentrations were detected in the produced wine. Among various clarifying agents studied, charcoal was the only one found to be effective for removing teflubenzuron residues from wine.
Asunto(s)
Benzamidas/análisis , Insecticidas/análisis , Rosales/química , Vino , Cromatografía Líquida de Alta PresiónRESUMEN
A method for the determination of the benzoylurea insecticides diflubenzuron, triflumuron, teflubenzuron, lufenuron and flufenoxuron in grapes and wine by HPLC has been developed and validated. Grape samples (50 g) were homogenized and extracted with ethyl acetate-sodium sulfate and further cleaned-up by solid-phase extraction on silica sorbent. Wine samples (10 ml) diluted with water (1:3) were solid-phase extracted on an octadecyl sorbent using methanol as the eluent. The pesticides were separated on a reversed-phase octadecyl narrow-bore column by gradient elution and the residues were determined with a UV diode array detector. The calibration plots were linear over the range 0.05-5 micrograms/ml. Recoveries of benzoylurea pesticides from spiked grapes (0.02-2.0 mg/kg) and wine (0.01-0.2 mg/l) were 85.8-101.6% and 69.1-104.8%, respectively, and the limits of quantification for these insecticides were < 0.01 mg/kg for grapes and < 0.01 mg/l for wine. The method was applied to the determination of flufenoxuron and teflubenzuron residues in grapes from treated fields and in produced wine.