Liu Shanshan, Bian Zhaoyang, Yang Fei, Li Zhonghao, Fan Ziyan, Zhang Hongfei, Wang Ying, Zhang Yange, Tang Gangling
China National Tobacco Quality Supervision and Test Center, Zhengzhou, 450001, People's Republic of China.
J AOAC Int. 2015 Mar-Apr;98(2):472-6. doi: 10.5740/jaoacint.14-089.
A method to determine residues of the three acid herbicides, 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, and 3,6-dichloro-2-methoxybenzoic acid (dicamba), in tobacco using LC/MS/MS is presented. Because these herbicide residues in tobacco might exist in different forms (free acid, salt, and ester), tobacco samples were first pretreated by alkaline hydrolysis and then the pH was adjusted in order to convert the residues completely to their free acid forms. Dichloromethane extraction and dispersive SPE using C18 sorbent were carried out before LC/MS/MS analysis, and quantification was performed using the internal standard method. Linearity was good for all analytes (R(2) ≥ 0.999) in the concentration range of 0.02 to 0.5 mg/kg. LODs were below 0.05 mg/kg. Recoveries ranged from 80.4 to 93.5%, and RSD was below 10%. This simple, efficient, and sensitive method can be applied to the determination of residues of the three acid herbicides in tobacco.
本文介绍了一种使用液相色谱-串联质谱法（LC/MS/MS）测定烟草中三种酸性除草剂，即2,4,5-三氯苯氧乙酸、2,4-二氯苯氧乙酸和3,6-二氯-2-甲氧基苯甲酸（麦草畏）残留量的方法。由于烟草中的这些除草剂残留可能以不同形式存在（游离酸、盐和酯），因此首先对烟草样品进行碱性水解预处理，然后调节pH值，以便将残留完全转化为游离酸形式。在进行LC/MS/MS分析之前，先采用二氯甲烷萃取和使用C18吸附剂的分散固相萃取法，并采用内标法进行定量分析。在0.02至0.5 mg/kg的浓度范围内，所有分析物的线性关系良好（R(2)≥0.999）。检测限低于0.05 mg/kg。回收率在80.4%至93.5%之间，相对标准偏差低于10%。这种简单、高效且灵敏的方法可用于测定烟草中三种酸性除草剂的残留量。
