Residues, dissipation, and risk assessment of spinosad in cowpea under open field conditions.
The dissipation and residues of an eco-friendly bio-pesticide, spinosad, in cowpea under field conditions were studied using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MSMS) after Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction. The method exhibited good linearity with respect to spinosyn A and spinosyn D in solvent or blank cowpea matrix with correlation coefficients>0.99. Additionally, matrix effects were not significant in the range 0.987-1.014, and the average recoveries at three concentration levels were 75.1-91.1 and 79.4-90.5% for spinosyn A and spinosyn D, respectively. The intra- and inter-day relative standard deviations were 2.5-9.3 and 7.8-9.8% for spinosyn A, respectively, and 4.1-7.9 and 6.6-8.3% for spinosyn D, respectively. The limits of detection (LODs) and limits of quantification (LOQs) were 0.005 and 0.01 mg kg(-1), respectively, for spinosyn A, and 0.002 and 0.005 mg kg(-1), respectively, for spinosyn D. The dissipation of spinosad (sum of spinosyn A and spinosyn D) fitted well to first-order kinetics with half-lives of 0.9-1.5 days. The highest residue (HR) at pre-harvest interval (PHI) of 12 h was 0.321 mg kg(-1). Compared with the maximum residue limit (MRL) set by Codex, a PHI of at least 24 h was recommended. The estimated daily chronic intake of spinosad from cowpea was less than 0.14% of the acceptable daily intake (ADI). Therefore, the risk of consuming cowpea sprayed with spinosad under recommended field conditions was considered acceptable for the Chinese population.
Hainan Provincial Key Laboratory of Quality and Safety for Tropical Fruits and Vegetables, Analysis and Testing Center, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China. huanzhibo@163.com.
Zhibo
Z
Huan
Hainan Provincial Key Laboratory of Quality and Safety for Tropical Fruits and Vegetables, Analysis and Testing Center, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China.
Jinhui
J
Luo
Hainan Provincial Key Laboratory of Quality and Safety for Tropical Fruits and Vegetables, Analysis and Testing Center, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China.
Zhi
Z
Xu
Hainan Provincial Key Laboratory of Quality and Safety for Tropical Fruits and Vegetables, Analysis and Testing Center, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China.
Defang
D
Xie
D002853:Chromatography, Liquid; D004338:Drug Combinations; D004784:Environmental Monitoring; D006207:Half-Life; D007700:Kinetics; D057230:Limit of Detection; D018942:Macrolides / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis*; D018570:Risk Assessment; D053719:Tandem Mass Spectrometry
D004338:Drug Combinations; D018942:Macrolides; D010573:Pesticide Residues; C114883:spinosyn A; C114884:spinosyn D; C415329:spinosad
Cowpea; Crop residues; Dissipation; Risk assessment; Spinosad; UPLC-MSMS