Cyantraniliprole is an anthranilic diamide insecticide used in seed treatment, but the insecticide can come into direct contact with the soil. In this work, the equilibrium sorption of the insecticide in soils with different attributes was studied. The sorption was low, characterizing the high leaching potential of the insecticide
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Analytical method Cyantraniliprole quantification was performed by chromatographic analysis using (HPLC) a Shimadzu model CBM—20A, equipped with high-pressure reciprocating pumps LC—10AD VP, a column oven CTO—10AS VP, a SIL—10AF autoinjector; Column C18: Shimadzu VP-ODS (150 X 4.6 mm, 5 µm) (Tokyo, Japan) and with UV/vis SPD detector—20A. The analysis conditions were: mobile phase acetonitrile: water (60:40); injection volume of 20 µL, a flow rate of 0.80 mL min-1; oven temperature 25°C, wavelength 270 nm. The total running time 7.0 minutes. Soils One soil sample was collected in Ponte Nova city, Minas Gerais, Brazil (sandy loam texture) located at coordinates 20°24'16.3"S 42°48 '49.5"W. Others two soil samples were collected in Viçosa, Minas Gerais, Brazil. The Viçosa1 (clay texture) was located at coordinates 20°45'47.6"S 42°50'24.7"W. The Viçosa2 (clay texture) was located at coordinates 20°46'11.2"S 42°52'09.3"W. After collection, the soils were de-roasted, homogenized, sieved through a 2 mm sieve, and air-dried at room temperature for 24 hours. They were then submitted to textural and physicochemical analyzes (Table 2). Sorption The sorption assays were made according to Organization for Economic Cooperation and Development (OECD) (OECD) (2000). The assays have been done for each soil separately. 2.00 g of soil were weighed in Falcon tubes (50.00 mL of capacity) and fortified with 10.00 mL of commercial product solution containing desired concentration of cyantraniliprole. The concentrations evaluated were 1.00; 2.00; 4.00; 6.00; 8.00 mg L-1. Subsequently, the tubes were subjected to vertical agitation using an orbital shaker at 40 rpm for 6 h at a temperature of 24 ± 2°C. After this time, the tubes were centrifuged for 7 minutes at 3500 rpm (SISlab G2300). The aliquots from supernatants were collected, filtered on PTFE membrane (0.45µm), and submitted to HPLC-UV/Vis analysis. The amount of cyantraniliprole adsorbed in the soil (Cs), in mg kg-1, was calculated by the difference between the initial concentration of the analyte added to the soil and the concentration quantified in the equilibrium solution (Ce) in mg L-1. Desorption After the sorption assay, the supernatant of each Falcon tube was discarded. Then, for each tube, were added 10.00 mL of CaCl2 solution (0.01 mol L-1) without cyantraniliprole. Afterward, the tubes were submitted to agitation, centrifugation (7 min at 3500 rpm), and filtering (PTFE membrane of 0.45 m), as described in the previous item. The amount of cyantraniliprole desorbed was determined by the difference between the amount sorbed in soil (Cs) and the concentration determined from supernatant collected after the desorption study.