The Application Research Of Liquid Phase Microextraction In Analysis Of Plant Volatile Constituents

Liquid-phase microextraction(LPME),a newly developed technology in recent years,appears to be a sample,rapid,sensitive and environmentally friendly choice.It incorporates sampling,extraction and enrichment into a single stage and is becoming a significant part in sample preparation field.In this paper,firstly,an overall study of sample pretreatment in Plant volatile constituents(PVOCs)analysis were carried out and afterwards LPME was introduced in detail,a review of the development and application of LPME followed with GC and GC/MS was presented.At last,the author pointed out that LPME had many advantages for PVOCs analysis,and evaluated the application of this method combined with personal experiments.(1)A rapid and sensitive static-HS-LPME followed by gas chromatography-mass spectrometry method was developed to determine VOCs in Fresh flowers of Edgeworthia chrysantha Lindl.Parameters relevant to the extraction performance were studied and optimized, afterward,a comparison between it and SPME was made.The results showed that the number of the volatile compounds identified by the two methods was 30 for SPME,and 25 for LPME,respectively.It was also found that the LPME method shared 21 compounds in common with SPME,which account for about 60%of the detected VOCs.From these detected compounds,benzaldehyde,myrcene,4-hexen-1-ol acetate,hexyl acetate,2-hexen-1-ol acetate,methyl benzoate got higher relative amount by LPME,we can explain this for solvent selectivity,n-butyl acetate got excellent selectivity for esters that were main components in E. chrysantha Lindl.Therefore,it can be known that HS-LPME method can be used as an alternative method for the analysis of fragrance constituents in E.chrysantha Lindl.(2)A dynamic-HS-LPME(organic solvent film extraction)method followed by GC/MS was established to identify VOCs in Mosla Chinensis Maxim.Experiment parameters were optimized,under the optimized conditions,p-Cymene(40.9%),γ-Terpinene(16.96%),β-Myrcene(4.78%),Thymol(4.52%),4-Carene(4.31%),Thymol acetate (2.86%),1R-α-Pinene(2.16%)were found to be the major constituents. We even had contrasted respective advantages and shortcomings of the static and dynamic mode.For the results,dynamic-HS-LPME got better enrichment effectively in less time,but in view of adding operations by hand,dynamic-HS-LPME was worse in reproducibility.(3)A new method was firstly advanced for PVOCs quantitative analysis——MHS-LPME.The author confirmed that "Linalool" was the uppermost main compounds(about 30%)in Lavender flowers VOCs by LPME method,next determined the quantity of Linalool in Lavender using MHS-LPME.Good reproducibility and linearity for the MHS-LPME was obtained.It is a solvent-free,cheap and sensitive technique,which eliminates possible memory effects as fresh solvent-drop is used for each extraction.The results showed liquid-phase micro-extraction and its improved were qualified to the extraction of PVOCs and Traditional Chinese Medicine(TCM)samples,which were faster,simpler,more sensitive and environmentally friendly.