固相萃取-高效液相色谱同时测定大米中的4种烟碱农药残留量

建立了高效液相色谱法同时测定大米样品中呋虫胺、噻虫胺、吡虫啉、吡虫清4种烟碱农药残留量的检测方法,对4种烟碱农药在ENVI-Florisil和Carb复合固相萃取柱上的保留行为进行了研究。样品用乙腈提取,固相萃取净化,HPLC-DAD分离检测,外标法定量。峰面积与标准溶液浓度在0.1～1.0 mg/L范围内呈良好的线性关系,相关系数大于0.9996。样品加标回收率为75.5%～96.0%,相对标准偏差为0.49%～4.36%(n=6),检出限达到0.004 mg/kg。     

水稻和土壤中呋虫胺残留的固相萃取/液相色谱-串联质谱分析方法

建立了呋虫胺在水稻(糙米、稻壳和稻草3种基质)和土壤中残留的液相色谱-电喷雾串联质谱(LC-ESI MS/MS)检测方法。各基质经乙腈提取,PSA柱净化后,以Agilent ZORBAX SB-C18色谱柱分离,电喷雾电离串联质谱正离子多重反应监测(MRM)模式进行测定。在不同加标水平下,对呋虫胺在4种不同基质中的回收率和相对标准偏差(RSD)进行测定。结果表明,呋虫胺在糙米中的回收率为73.8%~97.2%,RSD为3.1%~9.9%;在稻壳中的回收率为77.6%~80.3%,RSD为2.5%~5.8%;在稻草中的回收率为76.0%~94.0%,RSD为4.8%~8.8%;在土壤中的回收率为83.6%~93.3%,RSD为4.6%~6.4%。该方法具有样品前处理简单、快速、分析时间短的特点,灵敏度、准确度和精密度均符合农药残留检测要求。     

Residual levels and dietary risk assessment of bifenthrin and dinotefuran and its major metabolites in open wheat field conditions

To evaluate the residual levels of bifenthrin and dinotefuran, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) and high-performance liquid chromatography–tandem mass spectrometry method for simultaneous detection of bifenthrin and dinotefuran and its major metabolites in wheat was developed and validated. Dietary risk assessments were further performed based on the relevant residual data from 12 wheat fields, toxicology data and dietary patterns. In wheat grain and straw, the recoveries of all analytes ranged from 77 to 102% with the relative standard deviation <9.7% and the limit of quantitation 0.05 mg kg⁻¹. The highest terminal residue of bifenthrin in wheat grain was 0.069 mg kg⁻¹ and dinotefuran was 0.34 mg kg⁻¹. Residual concentrations of bifenthrin and dinotefuran decreased to <0.05 and 0.15 mg kg⁻¹ at 21 days (pre-harvest interval), respectively. The chronic risk quotient ranged from 6.4 to 62.7% and the acute risk quotient varied from 0.38 to 17.73%. The chronic and acute dietary risks caused by the terminal residues of the two insecticides were negligible for Chinese populations. The recommended pre-harvest interval was proposed to ensure safe wheat consumption. These data could provide a scientific reference to establish the Chinese maximum residue limit of dinotefuran in wheat.     

Ultra high performance liquid chromatography with tandem mass spectrometry method for determining dinotefuran and its main metabolites in samples of plants,animal‐derived foods,soil, and water

An ultra high‐performance liquid chromatography with tandem triple quadrupole mass spectrometry residue method was developed and validated for the quantification and identification of dinotefuran and its main metabolites 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea and 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) guanidine in fruit (watermelon), vegetable (cucumber), cereal (rice), animal‐derived foods (milk, egg, and pork), soil, and water. The samples were extracted with acetonitrile containing 15% v/v acetic acid and purified with dispersive solid‐phase extraction with octadecylsilane, primary secondary amine, graphitized carbon black, or zirconia‐coated silica prior to analysis. The method had an excellent linearity (R² ≥ 0.9942, 1–500 μg/L) and satisfactory recoveries (73–102%) at five spiked levels (0.001, 0.01, 0.05, 0.5, and 2 mg/kg) with intra‐ or interday precision in the range of 0.8–9.5% and 3.0–12.8% for the three compounds in the eight matrices. The limits of quantification were 10 μg/kg for 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) guanidine and 1 μg/kg for 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea and dinotefuran. The applicability of the developed method was demonstrated by determining the occurrence of dinotefuran, 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) guanidine, and 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea in various samples from plants, animal‐derived foods, and the environment. From 80 samples, 70 contained dinotefuran (0.8–11.7 μg/kg), among which six also contained 1‐methyl‐3‐(tetrahydro‐3‐furylmethyl) urea (water and rice, 0.5–0.9 μg/kg).     

呋虫胺衍生物杀虫活性的理论研究

基于Chem3D Ultra 7.0软件中的MOPAC半经验方法 AM1,计算了13种呋虫胺衍生物的19个量子化学和理化参数(包括ELUMO、EHOMO、△E=ELUMO-EHOMO、QC1、QC2、QN、QN1~QN4、QO、QO、μ、Hf、Ve、E0、Cv、Sm等)。采用最佳变量子集回归方法,建立呋虫胺衍生物对褐飞虱杀虫活性与上述结构参数的定量构效关系模型。结果表明,呋虫胺衍生物对褐飞虱杀虫活性的大小与ELUMO、QN1呈负相关,而与QC2正相关。所建的最优三变量模型具有良好的预报能力(R2=0.928、Rcv2=0.805、Rcv-22=0.797)和较高的稳健性(Radj2、F、VIF、t、AIC和FIT等检验)。设计与预测了4种新颖化合物的杀虫活性,在浓度为500mg/dm3下,它们的杀虫活性预测值均超过115%。所建模型可为化学工作者合成新型高效新烟碱类化合物提供理论参考。