Full
Outline
To investigate the residual dissipation behaviors and dietary risk of azoxystrobin and epoxiconazole in Oryza sativa straw, husk and brown rice using ultra performance liquid chromatography-tandem mass spectrometry.
The samples were directly extracted with acetonitrile aqueous solution, then vortexed and centrifuged. A certain amount of the supernatant was filtered and analyzed using ultra performance liquid chromatography-tandem mass spectrometry. Quantification was performed using the external standard method.
The limit of quantitation for azoxystrobin and epoxiconazole were both 0.05 mg/kg. The average recoveries of azoxystrobin and epoxiconazole were in the range of 91.9%–100.7%, respectively, with the relative standard deviations of 0.34%–4.19% at spiked levels from 0.05 mg/kg to 5.00 mg/kg. In contrasted to the traditional QuEChERS procedure, the proposed method eliminated the clean-up step, substantially decreased the usage of organic reagents, and enabled simpler and more rapid sample processing. The degradation dynamics of azoxystrobin and epoxiconazole residued in brown rice fitted the first-order kinetic equations, while the half-lives ranged from 1.04 to 17.54 d respectively. The highest residual amount of azoxystrobin and epoxiconazole in brown rice at 28 d after the last application were 0.26 mg/kg,0.44 mg/kg, which were lower than the maximum residue limit of 0.5 mg/kg established by China. The chronic dietary exposure risks for the general population, expressed as risk quotient, were 5.36% for azoxystrobin and 39.05% for epoxiconazole.
Application of 35% azoxystrobin, epoxiconazole suspension concentrate (containing 20% azoxystrobin and 15% epoxiconazole) according to the procedure established in this study will not cause unacceptable health risks to the general population via Oryza sativa consumption.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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