Suchergebnisse

AbstractThe investigation of the magnitude of residues after application of a pesticide is important to ensure consumer safety and is also a regulatory requirement to grant authorization. To address those issues, the behavior of trifloxystrobin residues was investigated in outdoor strawberry and cucumber cultivations, following the recommended and more critical agricultural practices under Egyptian dry climatic conditions. Fruits were collected at several pre-harvest intervals and analyzed with the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction protocol followed by liquid chromatography-tandem mass spectrometry. The limit of quantitation of the method was 0.001 mg kg−1. When trifloxystrobin was applied on the field, the half-lives were 2.4 days in cucumbers and 6.2 days in strawberries. Risk assessment showed that chronic and acute dietary exposure to residues following the investigated agricultural patterns are of no concern to consumers.

Abstract
Determination and dissipation kinetics of pymetrozine and spirotetramat in green bean were studied using a QuEChERS method coupled to high-performance liquid chromatography-tandem mass spectrometry. Pymetrozine recoveries ranged between 88.4–93.7%, with relative standard deviation (RSD) of 5.5–14.4%. For spirotetramat the recoveries ranged between 91.7–103.4%, and the RSD were in the range of 3.2 to 12.4%. The limits of quantification (LOQs) were 0.01 mg/kg and 0.005 mg/kg for pymetrozine and spirotetramat, respectively.The developed analytical method was used to study the degradation rates of pymetrozine and spirotetramat in green bean grown in open field. Results showed that pymetrozine and spirotetramat followed the first-order kinetics model with half-lives of 3.3 days and 4.2 days, respectively. Furthermore, risk assessment was carried out which showed that, the chronic risk quotient (RQc) values for pymetrozine and spirotetramat were much lower than 100%. The present results indicated that the health risks posed for consumers by the pymetrozine and spirotetramat residues were negligible at the recommended dosages.