张建平 黄朝章 余志强 谢卫 刘泽春 许寒春 蓝洪桥 邓其馨 黄延俊
摘 要:为降低烟草中噁霉灵检测中的基质干扰,提高检测灵敏度和和稳定性,通过试验建立了以QuEChERS为样品前处理方法、液相色谱串联质谱仪为检测仪器的烟草中噁霉灵残留检测方法。样品加水浸润后,经丙酮提取、盐析试剂包除水、石墨化炭黑除杂后,采用Agilent ZORBAX 300SB-C8液相色谱柱(2.1 mm×100 mm,1.8 μm)分离,甲醇-水程序洗脱,ESI雾化,串联质谱MRM检测。结果发现,该方法在0.0025~0.0500 mg/L范围内线性良好,决定系数r2=0.9996,定量检测限1.06 μg/L,回收率在90.8%~92.0%之间,相对标准偏差为5.1%。运用该方法测定烟草中的噁霉灵,操作简单,检测精度高,满足CORESTA对烟草农残检测的要求。
关键词:烟草;噁霉灵;超高效液相色谱串联质谱法
Abstract: In order to reduce matrix interference and improve detection sensitivity and stability, a method for determination of hymexazol residues in tobacco was established using QuEChERS as sample pretreatment method and liquid chromatography tandem mass spectrometer as detection instrument. The samples were extracted by acetone after moistened with water, then bytreated with salting-out reagent to remove water and purified by graphitized carbon black (GCB). After separated by Agilent ZORBAX 300SB- C8 column (2.1 mm×100 mm, 1.8 μm) with methanol-water as the mobile phase,the extracts were detected by an electrospray ionization (ESI) tandem mass spectrometry in the multiplereaction-monitoring (MRM) mode. The results showed that good linearity was obtained in the range of 0.0025-0.0500 mg/L, the linear correlation coefficient (r2) was 0.9996, the quantitative detection limit was 1.06 μg/L, the recovery ratio was between 90.8%-92.0%, and the relative stantdard deviation was 5.1%. With simple operation and high detection accuracy, this method is suitable for hymexazol determination in tobacco, which meets CORESTA's requirements for tobacco pesticide residue detection.
Keywords: tobacco; hymexazol; ultra performance liquid chromatography-tandem mass spectrometry
随着消费者对健康问题的关注,农药残留成为卷烟安全性的重点关注指标之一。噁霉灵(3-羟基-5-甲基异恶唑)作为土壤杀菌剂,在烟草、水稻、黄瓜、西瓜、甜菜等作物中广泛使用。噁霉灵毒性虽较低,但也存在农药残留问题,《食品中农药最大残留限量》国家标准明确要求噁霉灵在糙米和甜菜中的残留量不得高于0.50 mg/kg[1-2];烟草行业标准《烟叶农药最大残留限量》中规定噁霉灵在烟草中的最大残留(MRL)值为0.50 mg/kg,然而配套的YC/T405系列检测标准[3-7]中却缺少了噁霉灵相关检测方法。
目前报道的噁霉灵检测主要有气相色谱法[8-11]、电化学分析法[12-13]和液相色谱-紫外检测法[14-16]。其中气相色谱法因噁霉灵具有热不稳定性,需经衍生化才能进入气相色谱仪分析,且操作复杂、检测误差大;采用电化学分析法测定噁霉灵时选择性差,检测灵敏度低,多用于工艺跟踪和成品的定量分析;而液相色谱-紫外检测法测定噁霉灵时杂质干扰较大,不适用于烟草等复杂基质样品的检测。
鉴于现有检测手段的不足,本文尝试对传统液相色谱检测方法进行改进,建立一种以QuEChERS样品前处理结合液相色谱串联质谱仪检测为核心的烟草中噁霉灵残留量检测方法。
1 材料与方法
1.1 仪器和试剂
高效液相色谱仪(Agilent1290,美国Agilent公司);三重四级杆串接质谱仪(API5500,美国AB SCIEX公司);超纯水仪(Milli-Q,美国Millipore公司);漩涡混合振荡仪(VX-200,美国Labnet公司);高速离心机(Sigma1-14,德国Sartorius公司);电子天平(AG104型,感量:0.0001 g,瑞士Mettler Toledo公司)。
标准品:噁霉灵(Hymexazol),純度>99.5%,国家标物中心,磷酸三苯酯(Triphenyl phosphate,TPP),纯度>92%,德国Dr. Ehrenstorfer GmbH公司);N-丙基乙二胺键合固相(PSA)吸附剂、碳18(C18E)吸附剂、石墨化炭黑(GCB)吸附剂均购自美国Supelco公司;丙酮、乙腈、乙酸乙酯、甲醇为色谱纯;无水硫酸镁、氯化钠、柠檬酸钠、柠檬酸氢二钠为分析纯。
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