Gas Chromatography Residue Analysis of Bifenthrin in Pears Treated with 2% Wettable Powder

Bifenthrin Residues in Table Grapevine: Method Optimization, Dissipation and Removal of Residues in Grapes and Grape Leaves

The QuEChERS method was adjusted to determine bifenthrin residues in grapes and grape leaves. Extraction and cleanup procedures were optimized to decrease co-extracted materials and enhance the detection of bifenthrin. The method was validated per the European Union (EU) Guidelines criteria. Accuracy ranged from 98.8% to 93.5% for grapes and grape leaves, respectively. Precision values were 5.5 and 6.4 (RSDr) and 7.4 and 6.7 (RSDR) for grapes and grape leaves, respectively. LOQs (the lowest spiking level) were 2 and 20 µg/kg for grapes and grape leaves, respectively. Linearity as determination coefficient (R2) values were 0.9997 and 0.9964 for grapes and grape leaves, respectively, in a matrix over 1-100 µg/L range of analyte concentration. This was very close to the value in the pure solvent (0.9999), showing the efficiency of the cleanup in removing the co-extracted and co-injected materials; the matrix effect was close to zero in both sample matrices. Dissipation of bifenthrin was studied in a supervised trial conducted in a grapevine field during the summer of 2023 at the recommended dose and double the dose. Dissipation factor k values were 0.1549 and 0.1672 (recommended dose) and 0.235 and 0.208 (double dose) for grapes and grape leaves, respectively. Pre-harvest interval (PHI) was calculated for the Maximum Residue Limit (MRL) values of the EU database. Residues of bifenthrin were removed effectively from grapes using simple washing with tap water in a laboratory study. Residues reached the MRL level of 0.3 mg/kg in both washing treatments, running or soaking in tap water treatments for 5 min. Removal from leaves did not decrease residue levels to the MRL in grape leaves.

LC-MS/MS method for the simultaneous quantification of pyriproxyfen and bifenthrin and their dissipation kinetics under field conditions in chili and brinjal

Bifenthrin, a synthetic pyrethroid, and pyriproxyfen, a plant growth regulator, are used extensively in agriculture for controlling the different insect pests. The present study was undertaken to examine the dissipation behavior of a formulation with a combination of pyriproxyfen and bifenthrin on chili and brinjal under field conditions at four different locations. Dissipation study of combination of pyriproxyfen and bifenthrin revealed swift degradation in both crops with a half-life of 2.5-2.6 and 2.0-2.1 days in brinjal and chili, respectively. Also, a simple method for simultaneous quantification of pyriproxyfen and bifenthrin was developed and validated using modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique on liquid chromatography with tandem mass spectrometry (LC-MS/MS). Recovery of the method was found to be under an acceptable range of 90.0%-93.5% and 88.7%-94.3% in chili and 92.4%-96.6% and 97.4%-100.9% in brinjal for pyriproxyfen and bifenthrin, respectively. At harvest time, the terminal residues of bifenthrin and pyriproxyfen were below the maximum residue limits set by European Union in chili and brinjal, respectively, suggesting that the use of this pesticide formulation is safe and does not impose harmful effects on human health. PRACTICAL APPLICATION: In this paper, dissipation behavior of a pesticide formulation with a combination of pyriproxyfen and bifenthrin was undertaken under field conditions at four different locations on chili and brinjal in India. The simultaneous quantification of pyriproxyfen and bifenthrin using LC-MS/MS technique has been validated incorporating modified QuEChERS extraction method with limit of detection at 0.005 µg/g and limit of quantification at 0.01 µg/g, which is well below the EU-MRLs (European Union legislation Maximum Residue Level) of pyriproxyfen and bifenthrin in both chili and brinjal. Furthermore, dissipation kinetics of a formulation undertaken under field conditions at four different locations on chili and brinjal suggested that the terminal residues of both bifenthrin and pyriproxyfen were below the maximum residue limits set by European Union in chili and brinjal, respectively, at the time of harvest and that the use of this pesticide formulation is safe.