In order to determine the residual characteristics of fosthiazate and imidacloprid in spinach, the test pesticides, fosthiazate 30% SL and imidacloprid 8% SC, were diluted by 4,000- and 2,000-times, respectively, and then sprayed twice with a 7-day interval. Samples were collected on the day of harvest. The pesticide residues in spinach were analyzed with a high performance liquid chromatograph equipped with variable wavelength detector for fosthiazate and with diode array detector for imidacloprid. Limits of detection (LODs) were 0.02 for fosthiazate and 0.01 mg/kg for imidacloprid. Recoveries at two fortification levels of their 10×- and 50×LOD levels were 70.9-85.4 and 73.3-85.2 for fosthiazate and 84.9-85.3 and 85.3-86.2% for imidacloprid, respectively. Residual concentrations of the test pesticides in spinach were decreased time-coursely, while their residues were higher as spraying closer to the harvest day. The estimated daily intakes of two test pesticides by intake of spinach were less than 2.1% of its acceptable daily intake in all samples, representing that fosthiazate and imidacloprid residues detected in the test crop do not pose the immediate health risks.

Residual characteristics of fosthiazate and imidacloprid in spinach

256th National Meeting (2018)

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