Estimation of residues of Pyriproxyfen and Fenpropathrin in Chilli, Capsicum annum L.
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Date
2020
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DRPCAU, Pusa
Abstract
“Estimation of Residues of Pyriproxyfen and Fenpropathrin in Chilli, Capsicum annum L.” was carried at “Dr. Rajendra Prasad Central Agricultural University, Pusa” during 2019-2020. Representative samples of chilli at varying intervals after third spray were analysed following slightly modified QuEChERS techniques. Spraying of chilli crop with pyriproxyfen @ 50 and 100 and fenpropathrin @ 75 and 150 g a.i. ha-1 led to the initial residues ranging from 0.43 to 0.52 and 0.70 to 0.89 and 0.12 to 0.14 and 0.19 to 0.22 mg/ kg, correspondingly. Pyriproxyfen and fenpropathrin residues in chilli dissipated fast and found below limit of quantification later 3 and 5 days at low and high doses, accordingly. The T1/2 of pyriproxyfen in chilli were calculated to be 0.66 and 1.11 days whereas, for fenpropathrin, the values were 2.41 and 1.92 days. Residue of pyriproxyfen on chilli was found below the MRL of 0.02 mg/ kg after 2.97 days when practiced @ 50 g a.i./ha. However, residues for fenpropathrin on chilli collected 0 day after spray was below MRL following application @ 75 g a.i./ha. Therefore, experimental findings suggest a pre harvest interval of 3 and 1 day for pyriproxyfen and fenpropathrin at single dosage on chilli if followed good agricultural practices.
Among various household processing methods, boiling reduces 56.52 per cent residue followed by washing (50.65 per cent), dipping in salt solution (47.17 per cent), dipping in sodium bicarbonate solution (41.30 per cent), dipping in acetic acid solution
(39.78 per cent) and dipping in KMnO4 solution (39.13 per cent) after 0 (2hours after spray) day of treatment of pyriproxyfen @ 50 g a.i./ ha in chilli. Samples taken after 1 day of application when subjected to different household processing, the reduction per cent were ranged from 12.50 to 37.50 per cent with highest reduction with boiling and least with dipping in sodium bicarbonate solution. The mean initial deposits of fenpropathrin residue on chilli samples after third spray @ 75 g a.i./ ha accounted a loss of 72.50, 55.83, 52.50, 52.50, 50.00 and 41.67 per cent, as a result of dipping in KMnO4 solution, washing, boiling, dipping in sodium bicarbonate solution, salt solution and acetic acid solution, respectively. But in 1 day samples, the mean residue of fenpropathrin on chilli were BDL thereby, accounted the loss of 100 per cent.
Key words: Pyriproxyfen, fenpropathrin, residues, waiting period, household processing.