烟草中溴菌腈农药残留检测方法及消解动态

Residue Analysis and Dissipation of Bromothalonil in Tobacco

为摸清溴菌腈在烟草中的农药残留消解动态规律及残留特征,建立了QuEchERS 前处理和气相色谱-串联质谱（GCMS/MS）检测相结合的烟叶中溴菌腈残留量的分析方法.烟叶经乙腈提取,N-丙基乙二胺吸附剂（PSA）净化,气相色谱-串联质谱法检测.结果表明,在0.01-1.0 mg/kg 3 个添加水平下,溴菌腈在鲜烟叶和干烟叶中的平均回收率分别为85.8%-94.5%、83.2%-110.0%,相对标准偏差（RSD）分别为1.4%-10.6%、7.3%-14.1%,定量限（LOQ）均为0.01 mg/kg.利用山东和湖南2 年2 地的溴菌腈在烟叶中农药残留田间试验样品进行了深入研究,溴菌腈在烟叶中的半衰期7.8-14.9 d;按照162 g.a.i./hm2 和243 g.a.i./hm^2 剂量,分别灌根施药1-2 次,末次施药14 d 后,溴菌腈在烟叶样品中的最终残留量为0.010-0.13 mg/kg.根据烟草青枯病发病条件、发病时期、农药在烟叶中使用情况及OECD 农药残留限量计算结果,建议溴菌腈在烟叶中残留限量为0.2 mg/kg,安全间隔期为14 d.

To study residue and dissipation of bromothalonil in tobacco, a modified QuEChERS combined with gas chromatography triple quadrupole-tandem mass-spectrometry (GC-MS/MS) liquid chromatography-tandem mass spectrometry method was developed. Samples were extracted with acetonitrile, cleaned up with primary secondary amine (PSA), and then determined with GC-MS/MS. The results showed that the average recoveries of bromothalonil were 85.8%-94.5% and 83.2%-110.0%, with relative standard deviations (RSDs) of 1.4%-10.6% and 7.3%-14.1% in fresh and cured tobacco leaves, respectively. The limit of quantification (LOQ) of this method was 0.01 mg/kg for both fresh and cured tobacco leaves. The dissipation and terminal residues were investigated in Qingdao and Changsha, China from 2012 to 2013. The dynamic results showed that the half-life of bromothalonil in fresh tobacco leaves was 7.8-14.9 d. The terminal residues of bromothalonil in cured tobacco leaves were determined after the first and second application at levels of 162 g.a.i/hm-2 and 243 g.a.i/hm-2. The terminal residues were 0.010-0.13 mg/kg 14 days after the last application in cured tobacco leaves. Based on the tobacco bacterial wilt incidence conditions, the incidence period, the use of pesticides in tobacco and OECD MRL calculator findings, we recommend the residue limit of bromothalonil in tobacco leaves of 0.2 mg/kg, and the safety interval of 14 d.