气相色谱-氮化学发光检测法测定烟草中的苦参碱及消解动态研究

建立了简单、快速的鲜烟叶中苦参碱的测定方法。样品用0.01 mol/L的乙酸水溶液(pH 3.5)提取,强阳离子交换柱(SCX-SPE)净化,气相色谱-氮化学发光检测器(GC-NCD)测定。通过净化方法比较发现,SCX-SPE法比常规溶剂萃取法具有更好的净化效果。在选定的色谱条件下,苦参碱在0.15~15.0μg/mL范围内,其质量浓度与峰面积之间呈良好的线性关系,决定系数 R2=0.9997。对烟草空白样品进行添加回收试验,在0.05~0.4 mg/kg范围内其回收率在89.5%~91.6%之间,相对标准偏差(RSD)在2.7% ~3.6%之间,检测限(LOD)为0.03 mg/kg,能满足苦参碱在烟草样品中的残留检测。田间试验结果表明:苦参碱的消解动态曲线符合一级动力学方程,其在烟草中的半衰期为7.64 d,属易降解农药。

Determination and decline study of matrine residue in tobacco by gas chromatography-nitrogen chemiluminessence detector

A simple and rapid method for determination of matrine in fresh tobacco leaves has been established.Matrine in tobacco samples was extracted by 0.01 mol/L acetic acid solution(pH=3.5),then cleaned up with strong cation exchange-solid phase extraction(SCX-SPE) and determined by gas chromatography-nitrogen chemiluminessence detector(GC-NCD).Comparison of the cleanup effect between conventional solvent extraction and SCX-SPE was carried out.The results showed that SCX-SPE was more effective.Under the selected chromatographic conditions,the linearity between mass concentration and peak area was satisfied(R2=0.999 7) in the range of 0.15-15.0 μg/mL.At the spiked levels of 0.05-0.4 mg/kg in blank tobacco samples,the recoveries were 89.5%-91.6% with RSD of 2.7%-3.6%,respectively.The limit of detection(LOD) of this method was 0.03 mg/kg.The results could achieve residue demand of matrine in tobacco samples.Furthermore,field experiment results indicated that the curve of decline dynamics followed the first-order kinetics equation.The half-life of matrine were 7.64 days in tobacco,which indicated that matrine should be classified as easily degradable agrochemical.