title: Ultrasonic nebulisation extraction: extraction column coupled with liquid phase microextraction for analysis of the volatile organic compounds in Foeniculum vulgare Mill. as a model.
abstract: BACKGROUND
  As the concentrations of the volatile organic compounds are always low and their matrix is complex, it is necessary to pre-concentrate the volatile organic compounds before analysis. Ultrasonic nebulisation extraction with a self-made extraction column coupled with liquid phase microextraction is developed for the extraction of active constituents from spices.
  
  
  OBJECTIVE
  To develop an environmentally compatible extraction technique for the preparation and analysis of the volatile organic compounds from spices.
  
  
  METHODS
  The sample is placed into the nebulisation vessel of a nebulisation humidifier and a purging gas is blown through the vessel continuously. When the nebuliser is switched on, a ultrasonic fountain is formed by ultrasonic vibration and the target analytes are transferred from the sample solution to the vapour phase and then concentrated on the extraction solvent in the extraction column. After extraction for 3 min and allowed to stand upright for 5 min, the extract is analysed by GC and GC-MS. Different methods of comparison can then be carried out.
  
  
  RESULTS
  Optimum conditions were found to be: 30 μL of n-tetradecane as the extraction solvent, a flow rate for the purging gas of 40 mL/min, a purging time of 3 min and a standing time was 5 min. The contents of constituents in the extract obtained by the proposed method were close to those obtained by hydrodistillation (HD). Moreover, the proposed method achieves higher enrichment efficiency.
  
  
  CONCLUSIONS
  A method was developed for the extraction of volatile organic compounds from spices. The study has shown that it is a fast and environmentally sustainable technique.
authors.affiliation: College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Cui
authors.initials: C
authors.lastname: Yu
authors.forename: Jinjuan
authors.initials: J
authors.lastname: Yang
authors.forename: Yeqiang
authors.initials: Y
authors.lastname: Wang
authors.forename: Hongmin
authors.initials: H
authors.lastname: Wei
authors.forename: Hanqi
authors.initials: H
authors.lastname: Zhang
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Shi
mesh_terms: D030001:Foeniculum / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D059627:Liquid Phase Microextraction / Q000295:instrumentation* / Q000379:methods*; D009330:Nebulizers and Vaporizers; D013997:Time Factors; D014465:Ultrasonics; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000302:isolation & purification*
chemical_list: D055549:Volatile Organic Compounds