Dissipation of Pyrethroid Residues in Peppers, Zucchinis, and Green Beans Exposed to Field Treatments in Greenhouses:  Evaluation by Decline Curves

Abstract

Dissipation of seven pyrethroid insecticides under field conditions was evaluated on green beans, zucchinis, and peppers grown in experimental greenhouses (Almería, Spain). Pyrethroid residues were determined by high performance liquid chromatography using continuous on-line post-elution photoirradiation with fluorescence detection after dichloromethane extraction and cleanup on florisil phase cartridges. Mathematically defined decline curves were established by determining optimal relationships between pyrethroid residues and time. Different models were used to find these curves. The 1st-order model achieved the best adjustment to the experimental data in 42.9% of cases. The RF (root function) 1st-order model was the best in 33.3% of times. Each of the 1.5th- and 2nd-order models provided the best adjustment in a 9.5% of the cases. Finally, the RF 1.5th-order model was the most appropriate in only 4.8% of cases. Half-life times for these three vegetables were estimated from the optimal models. The preharvest intervals for the residues in these three vegetables was obtained, taking into account the maximum residue levels established by the existing legislation. They were all lower than the ones specified by the makers of commercial formulates, which ensures a safe enough consumption.

Behaviour of fenitrothion residues in leaves and soil of vineyard after treatment with microencapsulate and emulsified formulations

“…However, that interpretation is not always applicable, because the residues frequently diminish quicker at first and much more slowly at a later stage in comparison with the 1st-order model [20,21]. In the present work, the half-live (T/2) has been estimated (tables 5 and 6) from the optimal model as well as from the 1st-order model (when this model is not optimal) according to Timme et al [10,11].…”

Characterization of a fungal strain capable of degrading chlorpyrifos and its use in detoxification of the insecticide on vegetables

“…On the other hand, some insect pests and pathogens may also develop resistance or tolerance to the conventionally used pesticides due to their single mode of action and this leads to frequent application of pesticides at higher dosages (Gajbhiye 2004). Furthermore, pesticides often dissipate slower on greenhouse vegetables due to the hermetic environments in greenhouses (Aguilera-del Real et al 1999;Garau et al 2002;Hernandez Torres et al 2002;Martinez Galera et al 2003). The excessive and frequent application of pesticides may result in high levels of pesticide residues accumulated on vegetable products, which poses a potential health hazard to consumers (Bolognesi & Morasso 2000;Fan & Jackson 1989;Tweedy et al 1991).…”

HPLC-MS/MS Method for the Measurement of Insecticide Degradates in Baby Food

“…Those that have been evaluated the degradates by either examining the kinetics of insecticide degradation in food matrices or detecting the degradates themselves present in food. 9,14,17−19 Some of these examinations considered only loss of the parent compound. 18,19 Other studies of insecticide degradation measured only the insecticide degradates.…”

“…9,14,17−19 Some of these examinations considered only loss of the parent compound. 18,19 Other studies of insecticide degradation measured only the insecticide degradates. 12 Studies that evaluated only either the loss of the parent compound or the presence of degradates do not provide complete information on insecticide loss.…”