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Rice is contaminated with pesticides applied in pre and post-harvest. These contaminations could be reduced through household operations like washing and cooking. Therefore, in the present research, a pre-soaking rice cooking method was used to reduce pesticides residues. Response Surface Methodology with Central Composite Design was applied to minimize pesticides concentration by choosing the best soaking time and water:rice grain relation before cooking. A quadratic polynomial equation was obtained. Desirability function approach gave the optimal cooking conditions as 14 h soaking time and water:rice grain relation of 3. This process allowed a pesticide elimination of 100.0%, 93.5%, 98.4%, 98.5%, 99.0%, and 95.0%, of azoxystrobin, cyproconazole, deltamethrin, epoxiconazole, kresoxim-methyl and penconazole, respectively., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This investigation shows the pesticide distribution and reduction using three common household cooking methods. Extraction was performed using QuEChERS and solid phase microextraction methodologies for rice and water, respectively. Gas chromatography-mass spectrometry was used. Both methods showed good linearity (r 2  > 0.9996 and 0.9945), adequate recoveries (between 98.9 and 107.8% and 90.5-104.2%) and relative standard deviations lower than 4.5% and 7.0%, for rice and water, respectively. The initial concentration of deltamethrin, penconazole, kresoxim-methyl, cyproconazole, epoxiconazole and azoxystrobin, were 84.9, 242.2, 298.5, 230.7, 253.4 and 293.5 µg/kg, respectively. Washing and soaking water reduce pesticides only 0.40 to 4.28%. The pesticide reduction during cooking were 20.73 to 57.72%, 32.74 to 70.39%, and 68.87 to 87.50% for traditional, excess water, and pre-soaking rice methods, respectively. Pre-soaking rice with extra water before cooking proved to be the method that generates the greatest reduction., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

An analytical method for determination of azoxystrobin, cyproconazole, deltamethrin, epoxiconazole, kresoxim-methyl, and penconazole in rice, using QuEChERS extraction and a gas chromatography, was validated. Recoveries ranged within the 98.9-107.8 % range for all pesticides. Limits of detection and of quantification were 0.27 and 0.90 μg/kg for azoxystrobin, 0.26 and 0.88 μg/kg for cyproconazole, 0.25 and 0.84 μg/kg for deltametrhin, 0.22 and 0.72 μg/kg for epoxiconazole, 0.22 and 0.73 μg/kg for kresoxim-methyl and 0.23 and 0.77 μg/kg for penconazole, respectively. The expanded measurement uncertainty was lower than 20% for all pesticides. The occurrence of these pesticides was evaluated in 100 rice samples commercialised in different supermarkets. Residues of at least two pesticides simultaneously were found in 94 samples. The concentrations were lower than European and Argentinean legislative limits, with exception of epoxiconazole that in 36 rice samples was found in concentrations above the limit established in Argentina.