色谱

色谱

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两种离子源技术气相色谱-质谱法检测茶叶中酰胺类除草剂的残留量

沈伟健,徐锦忠,杨雯筌,沈崇钰,赵增运,丁涛,吴斌   

  1. Laboratory of Food, Jiangsu Entry-Exit Inspection and Quarantine Bureau,

    Nanjing 210001, China

  • 收稿日期:2007-03-26 修回日期:2007-06-16 出版日期:2007-09-30 发布日期:1985-03-25
  • 通讯作者: 沈伟健

Determination of Acetanilide Herbicide Residues in Tea by Gas

Chromatography-Mass Spectrometry with Two Different Ionization Techniques

SHEN Weijian, XU Jinzhong, YANG Wenquan, SHEN Chongyu, ZHAO Zengyun, DING Tao, WU Bin

  

  1. Laboratory of Food, Jiangsu Entry-Exit Inspection and Quarantine Bureau,

    Nanjing 210001, China

  • Received:2007-03-26 Revised:2007-06-16 Online:2007-09-30 Published:1985-03-25

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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40 μg/kg 3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2.0 μg/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。

关键词: 茶叶 , 电子轰击离子源, 负化学离子源, 气相色谱-质谱, 酰胺类除草剂

Abstract:

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.

Key words: acetanilide herbicides, electron impact ionization (EI), negative chemical ionization (NCI), tea-leaves , gas chromatography-mass spectrometry (GC-MS)