气相色谱-四级杆飞行时间质谱法测定大米中苯氧羧酸类除草剂残留

摘要

Objective:To test a GC-Q-TOF/MS method for determination of pesticide residue of 15 kinds of phenoxy-hydroxy-acid herbicides in rice. Methods:Study the chromatographic conditions, content of linearity,detection limit,recovery rate and relative standard deviationthe of detecting 15 kinds of phenoxy-hydroxy-acid herbicides in rice with acetonitrile extraction,Carbon SPE column puri-fication,three methyl silane diazomethane derivatization and gas chromatography quadrupole time-of-flight mass spectrometry( GC-QTOF MS ). The 15 kinds of phenoxy-hydroxy-acid herbicides includes 3,5-dichlorbenzoic acid,dicamba,MCPP,MCPA,2,4-DP,2,4-D,pentachlorophenol l,2,4,5-TP,chloramben,2,4,5-T,2,4-DB,bentazon,dinoseb,picloram,acifluorfen. The content of e-valuation on sale in Guiyang,15 kinds of Phenoxyacid herbicides in rice. Then,the content of 15 kinds of phenoxy-hydroxy-acid herbicides in rice in Guiyang was evaluated by the above methods. Results:15 kinds of phenoxy-hydroxy-acid herbicides were completly separated in 20 minutes. The linear relation was good between 0 . 05 mg/L~1 . 0 mg/L under the mass spectroscopy condition and the correlation was from 0. 997 4 to 0. 999 9. The mean recovery of three levels(0. 05,0. 1,0. 15 mg/L) was from 80. 1% to 101. 3%,and the precision and repeatability of RSD values were from 5. 8% to 9. 6%(n=5). The detection line was between 0. 001 mg/kg and 0. 006 mg/kg. 15 kinds of phenoxy-hy-droxy-acid herbicides were not detected in rice samples. Conclusion:The method is simple,rapid and with satisfactory recoveries that it can provide the scientific quarantine criterion for 15 kinds of phenoxy-hydroxy-acid herbicides in rice. 15 kinds of herbicides were not detected in rice in Guiyang city.%目的：建立测定大米中15种苯氧羧酸类除草剂农药残留量的气相色谱-四极杆飞行时间质谱（ GC-Q-TOF/MS）测定方法。方法：采用乙腈提取，Carbon固相萃取净化柱净化，三甲基硅烷化重氮甲烷衍生化，建立GC-Q-TOF/MS 法测定大米中15种苯氧羧酸类除草剂[3，5-二氯苯甲酸、麦草畏、2-甲-4-氯苯氧丙酸（MCPP）、2-甲基-4-氯苯氧乙酸（MCPA）、2，4-滴丙酸（2，4-DP）、2，4-二氯苯氧乙酸（2，4-D）、5-氯苯酚、2，4，5-三氯苯氧丙酸（2，4，5-TP）、草灭平、2，4，5-三氯苯氧基乙酸（2，4，5-T）、2，4-滴丁酯（2，4-DB）、苯达松、地乐酚、毒秀定、三氟羧草醚）]含量的色谱条件、线性关系、检测限以及回收率，考察相对标准偏差，采用该法评价随机抽样的贵阳市售大米中15种苯氧羧酸类除草剂的含量。结果：本研究设定条件下15种苯氧羧酸类除草剂在20 min内完全分离，并测得相应的色谱峰；在0.05~1.0 mg/L范围内线性关系良好，相关系数为0.9974~0.9999；3个添加水平（0.05、0.1及0.15 mg/L）的平均回收率为80.1%~101.3%；精密度和重复性的相对标准偏差（ RSD，n=5）为5.8%~9.6%；最低检出限（3S/N）在0.001~0.006 mg/kg；5种贵阳市售大米样品中未检出15种苯氧羧酸除草剂。结论：成功建立测定大米中15种苯氧羧酸类除草剂农药残留量的GC-Q-TOF/MS测定方法，贵阳市售大米中未检出15种苯氧羧酸类除草剂。