摘要
采用电子轰击(EI)和负化学(NCI)离子源两种离子源技术气相色谱-质谱联用法(GC-MS)测定了茶叶中12种酰胺类除草剂的残留量,并对两种方法进行了比较。样品经乙酸乙酯提取后,用串联的活性炭和弗罗里硅土柱选择性地富集茶叶中的待测组分,由气相色谱-质谱联用EI或NCI技术分时段选择离子监测方式进行测定。两种检测方法均简单快速,准确度和精密度高,在10,20和40μg/kg3个添加水平下的回收率为50%～110%,相对标准偏差(RSD)不大于10.9%。通过对两种离子源技术的对比研究发现,EI方法能够提供更多的碎片和结构信息,NCI方法能提供分子离子(相对分子质量)信息,两种信息互补,可提高定性的可靠度。NCI技术的选择性要明显好于EI技术;两种检测技术的灵敏度都较高,方法的定量限均不大于2.0μg/kg,在对含多个卤原子的酰胺类除草剂进行分析时,NCI技术的灵敏度比EI技术高1个数量级以上。
An analytical method of solid phase extraction-gas chromatography-mass spectrometry with two different ionization techniques was established for simultaneous determination of 12 acetanilide herbicide residues in tea-leaves. Herbicides were extracted from tea-leaf samples with ethyl acetate. The extract was cleaned-up on an active carbon SPE column connected to a Florisil SPE column. Analytical screening was determined by the technique of gas chromatography （GC）-mass spectrometry （MS） in the selected ion monitoring （SIM） mode with either electron impact ionization （EI） or negative chemical ionization （NCI）. It is reliable and stable that the recoveries of all herbicides were in the range from 50% to 110% at three spiked levels, 10 μg/kg, 20 μg/kg and 40 μg/kg, and the relative standard deviations （RSDs） were no more than 10.9%. The two different ionization techniques are complementary as more ion fragmentation information can be obtained from the EI mode while more molecular ion information from the NCI mode. By comparison of the two techniques, the selectivity of NCI-SIM was much better than that of EI-SIM method. The sensitivities of the both techniques were high, the limit of quantitative （LOQ） for each herbicide was no more than 2.0 μg/kg, and the limit of detection （LOD） with NCI-SIM technique was much lower than that of EI-SIM when analyzing herbicides with several halogen atoms in the molecule.
出处
《色谱》
CAS
CSCD
北大核心
2007年第5期753-757,共5页
Chinese Journal of Chromatography
基金
科技部"十五"科技攻关资助项目(2001BA804A17-02-01)
江苏省科技攻关(农业)资助项目(NoBE2003345)
关键词
气相色谱-质谱
负化学离子源
电子轰击离子源
酰胺类除草剂
茶叶
gas chromatography-mass spectrometry （GC-MS）
negative chemical ionization（NCI）
electron impact ionization （EI）
acetanilide herbicides
tea-leaves
