| The sample pretreatment is a crucial step in the analytical experiments.Drawbacks such as time-consuming,large quantity of organic solvent,complicated procedures always exsit in the traditional pretreatment.In order to overcome the disadvantages of the droplet which is hard to operate and easy to fall or volatilize in the extraction,and is not suitable for high-temperature and long-time extraction in headspace liquid-phase microextraction(HS-LPME),a novel sample pretreatment technology was developed in this paper,and the application in determining the volatile components of traditional Chinese medicine(TCM)was also reported.On the basis of headspace liquid-phase microextraction,a new pretreatment technique named as headspace liquid-phase liquid-phase extraction coupled with gas chromatography-mass spectrometry(HS-LP-LPE/GC-MS)was developed to separate and enrich volatile components.Polyethylene glycol(PEG)which was non-volatile with high boiling point was firstly employed as extraction agent to replace the conventional organic solvent,and the extraction temperature and extraction time were improved greatly.The problem which was easy to fall or volatilize in the extraction,due to the instability of the droplet,was solved by replacement of single drop hanging technology with increasing the amount of extraction agent.PEG layer was then back extracted by the organic solvent and was analyzed by GC-MS.The method overcame the shortage of small droplets which were easy to fall or volatilize in the extraction and were not suitable to high-temperature extraction by HS-LPME,and simultaneously,improved the sensitivity of water-soluble components in oil phase by steam distillation(SD).This paper introduced the design ideas,extraction device,operation steps of the new method,At the same time,the effect of parameters such as the amount of sample,extraction temperature and extraction time was studied.The new pretreatment technique was applied to analysis volatile components in Atractylodes macrocephala Koidz,The variable experimental conditions were optimized.The results indicated that 33 components accounting for 93.18%of the total components were identified by HS-LP-LPE,31 components accounting for 97.12%were identified by SD,and 17 components accounting for 98.24%by HS-LPME,and the volatile components extracted by HS-LPME could also be extracted by HS-LP-LPE.The content of the Atractylone was the highest in all three methods.By the experiment of methodology,it was shown that the method had fine repetition.Therefore,the HS-LP-LPE coupled with GC-MS method can be used for extracting and analyzing volatile components.A new method was developed for the determination of volatile components in traditional Chinese medicine:Ramulus Cinnamomi and Notopterygium incisum Ting ex H.T.Chang by HS-LP-LPE coupled with GC-MS.Parameters related to the extraction performance were studied and optimized,and then a comparison between the HS-LP-LPE and SD was made.The results showed that the volatile components were similar basically with a little difference in content.The new pretreatment technique was expected to be applied to the determination of more volatile components.The new pretreatment technique of HS-LP-LPE has been applied to determine the volatile components in three different Chinese traditional medicine successfully,Compared with pretreatment methods of HS-LPME and SD,the new method has the advantages of simple,fast,small amount of sample,low cost and good reproducibility.Some shortcomings like poor extraction efficiency of polar components in some aldehydes or alcohols still existed for its newly stuied.Further improvement and perfection were still needed. |
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