Acta Chimica Sinica ›› 2013, Vol. 71 ›› Issue (12): 1625-1632.DOI: 10.6023/A13070738 Previous Articles     Next Articles



欧阳永中a, 李操a, 周亚飞a, 周振b   

  1. a 东华理工大学江西省质谱科学与仪器重点实验室 南昌 330013;
    b 上海大学环境污染与健康研究所 上海 200444
  • 投稿日期:2013-07-14 发布日期:2013-10-02
  • 通讯作者: 李操
  • 基金资助:

    项目受国家杰出青年科学基金(No. 21225522)、国家自然科学基金(No. 21265001)、江西省科技支撑计划(No. 2010BNB00900,20113BCB24024)和南昌市2012年科技计划项目(No. 2012-sys-003)资助.

Rapid Analysis of Adulterated Chinese Liquor by Extractive Electrospray Ionization Mass Spectrometry

Ouyang Yongzhonga, Li Caoa, Zhou Yafeia, Zhou Zhenb   

  1. a Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China Institute of Technology, Nanchang 330013;
    b Institute of Environmental Pollution and Health, Shanghai University, Shanghai 200444
  • Received:2013-07-14 Published:2013-10-02
  • Supported by:

    Project supported by the National Science Fund for Distinguished Young Scholars (No. 21225522), Natural Science Foundation of China (No. 21265001), Jiangxi Science & Technology Pillar Program (No. 2010BNB00900, 20113BCB24024) and Nanchang Science & Technology Program of Jiangxi Province in 2012 (No. 2012-sys-003).

A novel analytical platform based on a home-made extractive electrospray ionization (EESI) source coupled with LTQ-XL mass spectrometer has been developed for fast and accurate identification of eight different kinds of adulterated Chinese liquors such as Maotai. Alcohol concentration in each liquor sample was measured by an alcohol meter and was adjusted to the same value by adding water and industrial alcohol. Measurements were done in positive ion detection mode under optimized experimental conditions. The ESI voltage was set to +4 kV, the pressure of the sheath gas (N2) was 1.2 MPa, the temperature of the heated capillary was set to 150 ℃, and the primary ions were created by electrospraying methanol/water/acetic acid mixture (4:4:2, V:V:V) at 5 μL·min-1. Normalized mass spectra of authentic and counterfeit liquors were differentiated by principal component analysis (PCA). Reproducibility of the method was characterized by cluster analysis (CA). Several constituents of liquor vapor were identified by tandem mass spectrometry (MS/MS). To perform MS/MS experiments, ions of interest were isolated with a mass-to-charge window width of 1.4 u. and then subjected to collision-induced dissociation (CID) with 16%~24% collision energy for 30 ms. The analysis time for a single sample was less than 1 min. The accuracy of identification predicted by PCA was 96.5%. The feasibility of this method was verified by testing several unknown samples. In addition to EESI-LTQ-MS, volatile compounds in Maotai vapor were also studied by single photon ionization time-of-flight mass spectrometry (SPI-TOF-MS), and molecular fingerprints obtained by these two methods were compared. These two detection means showed their respectively outstanding advantages and synergy for the analysis of volatile organic compounds (VOCs). The introduced method provides an important tool for the quality control of alcoholic beverages with high speed and simplicity of analysis on the market.

Key words: extractive electrospray ionization, mass spectrometry, identification, principal component analysis, cluster analysis, single photon ionization, adulterated Chinese liquor