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Subject: Chemistry × Author: Pooja × End date: 2023 × Start date: 2022 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Persistance and decontamination studies of a combination formulation (pyriproxyfen 5% EC + fenpropathrin 15% EC) in okra and soil
    (CCSHAU, Hisar, 2023-02) Pooja; Sushil
    This study developed and validated a methodology for extracting the residues utilizing the QuChERS method, as well as the conformation and quantification of Pyriproxyfen and Fenpropathrin residues using GC-MS/MS working at low LOQ (0.01 mg kg-1). The field application of recommended (37.5 + 112.5 g a.i. ha-1) and double recommended dose (70 + 225 g a.i. ha-1) leads to initial deposits of Pyriproxyfen (0.359, 0.584 mg/kg) and Fenpropathrin (0.643, 0.951 mg /kg) which dissipated by following first order kinetics with half-life value ranged in between 1.79-1.84 (Pyriproxyfen) and 2.27-2.31 days (Fenpropathrin) at T1-T2 doses, respectively. The estimated pre-harvest intervals (PHI) for Pyriproxyfen and Fenpropathrin were 6.03 and 11.51, 0.91 and 2.54 days at T1 and T2 doses, respectively. There were no residues of Pyriproxyfen and Fenpropathrin in the soil after 1 day of the application of sumiprempt formulation indicating its safety for the next crop. Even though all the decontamination processes were successful in reducing the levels of both chemicals left behind, washing + boiling proved to be the most efficient. Residues of Pyriproxyfen and Fenpropathrin persisted for a little longer period in soil under laboratory conditions. ZIF-8 was synthesized by hydrothermal, sonochemical, and microwave-assisted methods, and its structural, physical, and chemical characteristics were investigated using FTIR, XRD, SEM, BET, and zeta seizer. ZIF-8 achieved a 69%, and 65 % removal of Pyriproxyfen and Fenpropathrin (20 mg/L) under optimized conditions, respectively.
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    ThesisItemOpen Access
    Dissipation, decontamination and leaching behaviour of thiamethoxam + λ cyhalothrin (ready mix) in soil and chilli
    (Chaudhary Charan Singh Haryana Agricultural University hisar, 2022-09) Pooja; Sushil
    The study reports the persistence as well as the decontamination pattern of insecticides, λ -cyhalothrin and thiamethoxam in chilli fruits following spray application of their ready-pre mix. For extraction and clean-up, three two different methods namely liquid-liquid partitioning and QuEChERS with clean-up were used in association with GC-MS/MS. The LOD and LOQ of the method determined were 0.01 μg g−1 and 0.005 μg g−1, respectively, and all the recoveries were found above the range of 80 per cent. Thiamethoxam persistent up to day 15 in both the doses with half-lives of 3.45 and 3.90 days respectively. While λ -cyhalothrin persisted up to day 5th with half-lives of 1.49 and 1.52 days. Washing followed by frying was observed to be the best method of decontamination. It was followed by washing with 1 % vinegar solution, 2 % salt solution, 2% tamarind with least in case of washing with water. No presence of λ -cyhalothrin and thiamethoxam residues were reported in chilli fruits which were much below their respective maximum residue limits (MRLs). In leaching experiment around 90 per cent of the residues were recovered totally, with no residues in leachates.