Residues of the fungicide epoxiconazole in rice and paddy in the Chinese field ecosystem

Abstract

Epoxiconazole is extensively used as fungicide in cereals, grapes and other crops worldwide. Rice is one of the world's most important food crops. Many people who depend on rice for their food live in Asia. A method employing liquid chromatography-tandem mass spectrometry was developed for determination of epoxiconazole in brown rice, straw, rice hull, paddy water and soils. Epoxiconazole residues in rice hull, brown rice, straw and soil were also determined. The limit of quantitation was set at 0.01 mg kg(-1) for the matrices studied. Epoxiconazole degradation in straw, paddy water and soil was studied. The epoxiconazole residues in brown rice, straw, hull and paddy soil were determined. Concurrent recoveries were between 89.2 and 104.1%, with relative standard deviations ranging from 4.6 to 14.4% at three fortification levels between 0.01 and 5.0 mg kg(-1). The half-lives in straw, paddy water and soils were found to be 4.7-5.9, 2.9-6.0 and 2.9-6.4 days respectively. The maximum residues in brown rice, straw, hull and paddy soil samples were 0.18, 2.47, 2.54 and 0.09 mg kg(-1) respectively. Compared with the maximum residue levels (MRLs) for epoxiconazole in rice that have been set by the European Union (0.1 mg kg(-1)) and by China (0.5 mg kg(-1)), the epoxiconazole residue on rice at an application rate of 112.5 g AI ha(-1) with two applications at an interval of 7 days, and with a 28 day preharvest interval (PHI), is below the MRL, and thus the use of epoxiconazole is considered to be safe. Epoxiconazole should be applied correctly, according to good agricultural practice, using only the recommended amounts, frequencies and appropriate PHI.